Active matrix type display apparatus, method for driving the same, and display element

ABSTRACT

An active matrix type display apparatus is provided that is inexpensive, has less crosstalk, has no flickering and a brightness gradient, and is suitable for a large screen size. The display apparatus includes a plurality of pixel electrodes arranged in a matrix, switching elements (TFTs) connected thereto, scanning electrodes, video signal electrodes, common electrodes, and a counter electrode, wherein liquid crystal, for example, is interposed between the pixel electrodes and the counter electrode. Assuming that a gate-drain capacitance is C gd , a common electrode-pixel electrode capacitance is C st , and the total capacitance connected to the pixel electrodes is C tot  in this configuration, α gd  and α st  represented by α gd =C gd /C tot , α st =C st /C tot  are set to be different values between a portion close to feeding ends in a screen and a portion away therefrom.

TECHNICAL FIELD

The present invention relates to an active matrix type display apparatususing a switching element such as a thin film transistor, a method fordriving the same, and a display element.

BACKGROUND ART

A display apparatus, for example, a liquid crystal display apparatuswidely is used for various kinds of electronic equipment as a thin andlight-weight flat display. In particular, an active matrix type liquidcrystal display apparatus using a switching element such as a thin filmtransistor (TFT) actively is being applied to a monitor display for apersonal computer, a liquid crystal TV, and the like due to itsexcellent image characteristics.

First, the basic configuration of an active matrix type displayapparatus will be described with reference to FIG. 3. The displayapparatus roughly is composed of a scanning signal driving circuit 21, avideo signal driving circuit 22, and a display element 23. The displayelement includes, as its main components, a plurality of pixelelectrodes 5 disposed in a matrix, a plurality of switching elements 3(generally, a thin film transistor (TFT) or the like is used) arrangedcorresponding to the pixel electrodes 5, and a plurality of scanningelectrodes 1 disposed in a line direction (horizontal direction) and aplurality of video signal electrodes 2 arranged in a column direction(vertical direction) corresponding to the matrix arrangement of thepixel electrodes. The video signal electrodes 2 are connectedelectrically to the pixel electrodes 5 via the switching elements 3.Furthermore, a counter electrode 20 is provided so as to oppose thepixel electrodes 5, and a display medium such as liquid crystal isinserted between the pixel electrodes 5 and the counter electrodes 20.Furthermore, electrodes called common electrodes 4 are provided inparallel with the scanning electrodes 1, and storage capacitors 7 areprovided between the common electrodes 4 and the pixel electrodes 5. Thevideo signal driving circuit 22 supplies a video signal to a pluralityof video signal electrodes 2 of the display element 23. Furthermore, thescanning signal driving circuit 21 supplies a scanning signal forcontrolling conduction of the switching elements 3 to a plurality ofscanning electrodes 1 of the display element 23.

JP 5(1993)-143021 discloses a method for driving an active matrix typeliquid crystal display apparatus. According to this method, wiringcalled common electrodes is provided in parallel with scanningelectrodes (gate electrodes or gate lines), storage capacitors areformed between the common electrodes and the pixel electrodes, thepotential of the common electrodes is varied in synchronization withthat of the scanning electrodes, and a superimposed voltage is appliedto the potential of the pixel electrodes by capacitive coupling throughthe storage capacitors. Because of the effect of the superimposition ofa voltage, a decrease in a video signal voltage (source voltage), areduction in driving power, enhancement of response speed and drivingreliability, and the like are achieved.

FIG. 14 is an equivalent circuit diagram of one pixel of a liquidcrystal display apparatus in which a storage capacitance C_(st) (C_(st)is a common electrode-pixel electrode capacitance in more general terms)is formed between a common electrode and a pixel electrode. FIG. 15 is adiagram illustrating the potential of each portion in the case where theliquid crystal display apparatus 1 is driven. In FIG. 14, TFT representsa thin film transistor, C_(gd) represents a gate-drain capacitance(scanning electrode-pixel electrode capacitance), C_(lc) represents apixel electrode-counter electrode capacitance (which is a capacitancemainly from liquid crystal; however, there also is a capacitancecomponent generated by electrical addition in series or in parallel fromthe other medium. Alternatively, such a capacitance may be appliedintentionally) formed between a pixel electrode and a counter electrodeprovided so as to oppose the pixel electrode with liquid crystalinterposed therebetween, V_(g)(n) represents the potential of a scanningelectrode, V_(s) represents the potential of a video signal, V_(d)represents the potential of a pixel electrode, V_(d) represents thepotential of a counter electrode, and V_(c)(n) represents the potentialof a common electrode. The pixels are arranged in a matrix, and V_(g)and V_(c) are provided with a suffix “n” since the n-th pixel is paidattention to.

A plurality of scanning electrodes, and the like are arranged in amatrix. For a strict definition, based on a scanning electrode, a pixel(generally, there are a plurality of such pixels) whose ON/OFF (of aTFT) is controlled by the scanning electrode may be referred to as “apixel belonging to the scanning electrode”. In contrast, based on apixel (or a pixel electrode), a scanning electrode that controls ON/OFFof a TFT of the pixel may be referred to as “a scanning electrode of thestage concerned”. The pixel electrode (V_(d)) in FIG. 14 refers to “apixel electrode belonging to the scanning electrode (V_(g)(n)), and thescanning electrode (V_(g)(n)) refers to “a scanning electrode of thestage concerned with respect to the pixel (V_(d)). Hereinafter, unlessotherwise specified, the term “pixel (electrode)” or “scanningelectrode” simply will be used.

There also are a plurality of common electrodes. Therefore, in the caseof strictly specifying a common electrode, the expression “commonelectrode that is the other connection destination of storagecapacitance connected to a pixel electrode” or the like will be used.The common electrode (V_(c)(n)) in FIG. 14 refers to “a common electrodethat is the other connection destination of storage capacitanceconnected to the pixel electrode (V_(d))”. However, this also will besimply referred to as “a common electrode”.

As shown in FIG. 15, in an odd-numbered frame, a video signal voltagetakes a negative value based on V_(d) (i.e., V_(sig)(−)). When thepotential of a scanning electrode V_(g) becomes an ON level (firstpotential level of a scanning electrode) V_(gon), a TFT is brought intoconduction (ON state), and the potential of a pixel V_(d) is charged toV_(sig)(−). At this time, the potential of a common electrode has avalue V_(c)(−) (second potential level of a common electrode). Then,under the condition that V_(g)(n) is at an OFF level (second potentiallevel of the scanning electrode) V_(goff), the TFT is brought out ofconduction (OFF state). Thereafter, when the potential of the commonelectrode is changed in a downward direction i.e., from V_(c)(−) toV_(coff) (third potential level of the common electrode), the pixelpotential V_(d) is superimposed with a coupling voltage proportional tothe voltage difference in a downward direction (arrow in FIG. 15).

In an even-numbered frame, a video signal voltage takes a positive valuebased on V_(d) (i.e., V_(sig)(+)). When a pixel is charged toV_(sig)(+), the potential of the common electrode is set at V_(c)(+)(first potential level of the common electrode). After discharging iscompleted and the potential of the scanning electrode falls, thepotential of the common electrode is changed from V_(c)(+) to V_(coff)in an upward direction. The pixel potential V_(d) is superimposed with acoupling voltage proportional to the voltage difference in an upwarddirection.

Consequently, while a voltage with a small amplitude (V_(sig)(+) andV_(sig)(−) is applied to a video signal electrode, a pixel electrode canbe supplied with a voltage with a larger amplitude (V_(do)(+) andV_(do)(−)). For example, by using an IC for a video signal of an outputvoltage range of 5 V, a voltage range applied to liquid crystal can beincreased to 10 V or 15 V. Thus, while using an IC with a low withstandvoltage, the liquid crystal can be driven with a voltage equal to orhigher than the withstand voltage.

A period during which the potential of the common electrode becomesV_(c)(+) or V_(c)(−) will be referred to as a common electrodecompensating period, and the voltage V_(c)(±) will be referred to as acommon electrode compensating voltage (compensating potential). Althoughit is desirable that V_(c)(+) is different from V_(c)(−), V_(coff) maybe the same voltage as either V_(c)(+) or V_(c)(−). Furthermore, thepotential of the common electrode is not always required to be eitherV_(c)(+) or V_(c)(−) while the potential of the scanning electrode isV_(gon). The potential of the common electrode should be at this valueat least when the scanning electrode falls from V_(gon) to V_(goff)(more specifically, when a TFT is changed from an ON state to an OFFstate).

The scanning signal driving circuit has two output levels, and thecommon electrode potential control circuit has three output levels. Morespecifically, the scanning signal driving circuit has a first potentiallevel V_(gon) and a second potential level V_(goff), and the commonelectrode potential control circuit has a first potential levelV_(c)(+), a second potential level V_(c)(−), and a third potential levelV_(coff). In general, three power sources are required of the commonelectrode potential driving circuit so as to correspond to theabove-mentioned three potential levels. However, if either one of thefirst potential level V_(c)(+) or the second potential level V_(c)(−) ismade equal to the third potential level V_(coff), only two power sourcesare enough. Even in the case where either of the compensating potentialsis equal to V_(coff), the potential levels are considered to bedifferent, so that three potential levels are considered to be present.

It is simply that the above-mentioned superimposition of a voltage isconservation of charge on a pixel electrode from a different point ofview. More specifically, during a period from a time immediately beforecharging of a pixel is completed and the potential of a scanningelectrode falls (the potential of the scanning electrode is V_(gon)) toa time when the common electrode compensating period is completed,charge of the pixel electrode is stored. Therefore, in each of theodd-numbered frame and the even-numbered frame, the following (Formula11) is obtained.C_(gd)(V_(sig)(−)−V_(gon))+  (Formula 11)C_(st)(V_(sig)(−)−V_(c)(−))+C_(lc)(V_(sig)(−)−Vd)=C_(gd)(V_(do)(−)−V_(goff))+C_(st)(V_(do)(−)−V_(coff))+C_(lc)(V_(do)(−)−V_(d))C_(gd)(V_(sig)(+)−V_(gon))+C_(st)(V_(sig)(+)−V_(c)(+))+C_(lc)(V_(sig)(+)−V_(d))=C_(gd)(V_(do)(+)−V_(goff))+C_(st)(V_(do)(+)−V_(coff))+C_(lc)(V_(do)(+)−V_(d))

The following (Formulae 12) are obtained by modifying Formula 11.V_(do)(−)=V_(sig)(−)−α_(st)ΔV_(c)(−)−α_(gd)ΔV_(gon)V_(do)(+)=V_(sig)(+)−α_(st)ΔV_(c)(+)−α_(gd)ΔV_(gon)  (Formula 12)

ΔV_(gon), ΔV_(c)(+), ΔV_(c)(−), and α_(gd), α_(st) are represented bythe following (Formula 13) and (Formula 14).ΔV_(gon)=V_(gon)−V_(goff)ΔV_(c)(+)=V_(c)(+)−V_(coff)ΔV_(c)(−)=V_(c)(−)−V_(coff)  (Formula 13)α_(gd)=C_(gd)/C_(tot)α_(st)=C_(s)/C_(tot)C_(tot)=C_(gd)+C_(lc)+C_(st)  (Formula 14)

In both (Formulae 12), the second term of the right side corresponds toa superimposed portion by a (capacitive) coupling voltage from thecommon electrode, and is determined by ΔV_(c)(+) or ΔV_(c)(−). ΔV_(c)(+)or ΔV_(c)(−) is a value of a potential (in this case, V_(c)(+) orV_(c)(−)), at a moment when a pixel is charged, of a common electrode towhich storage capacitance is connected, based on the potential (in thiscase, V_(coff)) in a retained state. The third term of the right side of(Formulae 12) is a (capacitive) coupling voltage from a scanningelectrode, and is called a feedthrough. C_(tot) in (Formula 14) can beconsidered as the total capacitance electrically connected to the pixelelectrode.

As described with reference to FIG. 15, the pixel electrode is chargedwith a signal voltage with its polarity inverted per frame. At thistime, it may be possible that the entire screen is set at the samepolarity, and the polarity is inverted per frame (field inversionsystem). In addition, there are a system of inverting the polarity perline (line inversion system), a system of inverting the polarity percolumn (column inversion system), and a system of inverting the polarityin a checkered pattern by combining the line inversion and the columninversion (dot inversion system). A charging pattern of a pixel by eachsystem is drawn as in FIGS. 16A, 16B, 16C, and 16D. Voltage waveformsapplied to video signal electrodes V_(SP) and V_(SQ) adjacent to eachother can be drawn as shown on the right side of each figure.

In the case of the field inversion and the column inversion, thepolarity of a video signal applied to a video signal electrode in oneframe is constant. However, in the case of the line inversion and thedot inversion, the polarity of a video signal is inverted every timeeach scanning electrode is selected. Furthermore, in the case of thefield inversion and the line inversion, the polarity is the same betweenthe adjacent video signal electrodes. However, in the case of the columninversion and the dot inversion, the polarity becomes opposite betweenthe adjacent video signal electrodes. In the case of the columninversion and the dot inversion, the video signal driving circuit has afunction of simultaneously applying two kinds (i.e., positive polarityand negative polarity) of video signals having different polarities to aplurality of video signal electrodes.

Among the respective systems, S. Tomita et al. (Journal of the SID, ½(1993), pp. 211-218) describe in detail that horizontal crosstalk islikely to occur in the field inversion and the line inversion.Hereinafter, this will be summarized.

In the field inversion and the line inversion, when a scanning electrodeis selected to charge pixel electrodes, all the pixel electrodes arecharged with the same polarity. More specifically, the potential ofpixel electrodes in the corresponding line changes from a negativevoltage to a positive voltage in the case of the even-numbered field,and the potential of pixel electrodes in the corresponding line changesfrom a positive voltage to a negative voltage in the case of theodd-numbered field. Then, the potential of a counter electrodefluctuates via the capacitance (liquid crystal capacitance also isincluded) between the pixel electrodes and the counter electrode (sincethe counter electrode has a finite sheet resistance, even if thepotential is fixed at the end of a screen, the potential slightlyfluctuates in the screen), the potential charged to the pixel alsofluctuates due to the influence; as a result, crosstalk may occur. Thisalso may be considered to occur since V_(d) appearing on both sides of(Formula 11) due to the fluctuations in the potential of a commonelectrode become different values between the left side and the rightside, and the retention potential V_(do)(±) of the pixel electrode doesnot become a value represented by (Formula 12).

In contrast, in the case of the column inversion and the dot inversion,when scanning electrodes in a line are selected to charge pixels, thepolarity of charging is opposite between adjacent pixels. Therefore, thefluctuations in the potential of the common electrodes via the pixelelectrode-common electrode capacitance cancel each other, whereby theabove-mentioned crosstalk does not occur.

For the above-mentioned reasons, it is desirable to adopt the columninversion or the dot inversion.

However, in a liquid crystal display apparatus that changes thepotential of a common electrode by the driving method as described inFIG. 15 with the circuit configuration in FIG. 3, the following becomesapparent: as a screen size increases, flickering and a brightnessgradient (brightness inconsistency) occur conspicuously.

Furthermore, when a screen size increases, the potential of a counterelectrode for writing a video signal fluctuates largely, and horizontalcrosstalk becomes conspicuous. Therefore, it is required to adopt thecolumn inversion or the dot inversion that is a driving systemadvantageous to horizontal crosstalk. However, in the case of adoptingthe driving method of FIG. 15 with the circuit configuration of FIG. 3,by controlling the potential of a common electrode at a moment when ascanning electrode is selected, a predetermined superimposed voltagewith the same polarity as that of a video signal is applied to all thepixels belonging to this line to obtain the effect of an increasedamplitude of the retention potential of pixel electrodes. Therefore, inthe case of the driving system in which a video signal with positive andnegative polarities is applied while a scanning electrode is selected asin the column inversion and the dot inversion, the effect of anincreased amplitude of the retention potential of a pixel electrodecannot be obtained (more specifically, the voltage of a video signaldriving circuit IC cannot be lowered). More specifically, the problemsin the prior art lie in that a video display apparatus capable oflowering the voltage of the video signal driving circuit IC and reducinghorizontal crosstalk cannot be achieved.

DISCLOSURE OF INVENTION

The present invention has been achieved in view of the above-mentionedproblems, and its object is to provide a display apparatus capable ofreducing flickering and a brightness gradient, and lowering the voltageof a video signal driving circuit IC and reducing horizontal crosstalk,a method for driving the same, and a display element.

In order to achieve the above-mentioned object, a first displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes; video signal electrodes; common electrodes; acounter electrode; a display medium interposed between the pixelelectrodes and the counter electrode; and storage capacitance formedbetween the pixel electrodes and the common electrodes,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(st), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

It is preferable that the first display apparatus includes a videosignal driving circuit for applying two kinds of video signals havingdifferent polarities to video signal electrodes in accordance with adisplay period.

Furthermore, it is preferable that the first display apparatus includesa common electrode potential control circuit for applying a voltagesignal to a plurality of common electrodes and a scanning signal drivingcircuit for applying a voltage signal to a plurality of scanningelectrodes, the common electrode potential control circuit has outputpotential levels of at least two values, and the scanning signal drivingcircuit has output potential levels of at least two values.

It is preferable that a potential of a scanning electrode becomes afirst potential level V_(gon) when the scanning electrode is selectedand becomes substantially a second potential level V_(goff) during aretention period in which the scanning electrode is not selected,

a potential of a common electrode that is a connection destination ofstorage capacitance connected to pixel electrodes of a plurality ofpixels belonging to the scanning electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal is positiveand a second potential level V_(c)(−) in a case where the polarity ofthe video signal is negative, when the scanning electrode is selected,and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(st)V_(cp)/2  (Formula 2)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 3))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of γ in theportion close to the feeding ends in the screen is γ(O), a value of γ inthe portion away from the feeding ends in the screen is γ(E), and avalue of γ in a portion in a middle therebetween in terms of a distanceis γ(M), γ(M) is smaller than [γ(O)+γ(E)]/2.

Furthermore, it is preferable that V_(cp) takes a negative value.

In the first display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

a potential of a common electrode that is a connection destination ofstorage capacitance connected to pixel electrodes of a plurality ofpixels belonging to the scanning electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal is positiveand a second potential level V_(c)(−) in a case where the polarity ofthe video signal is negative, when the scanning electrode is selected,and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

β represented byβ=α_(gd)+α_(st)(ΔV_(cc)/ΔV_(gon))  (Formula 4)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 5))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of β in theportion close to the feeding ends in the screen is β(O), a value of β inthe portion away from the feeding ends in the screen is β(E) and a valueof β in a portion in a middle therebetween in terms of a distance isβ(M), β(M) is larger than [β(O)+β(E)]/2.

Furthermore, it is preferable that ΔV_(cc) is negative.

In the first display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

a potential of a common electrode that is a connection destination ofstorage capacitance connected to pixel electrodes of a plurality ofpixels belonging to the scanning electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal is positiveand a second potential level V_(c)(−) in a case where the polarity ofthe video signal is negative, when the scanning electrode is selected,

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(st)V_(cp)/2  (Formula 2)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 3))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto, and

β represented byβ=α_(gd)+α_(st)(ΔV_(cc)/ΔV_(gon))  (Formula 4)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 5))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In order to achieve the above-mentioned object, a second displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes; video signal electrodes; common electrodes; acounter electrode; a display medium interposed between the pixelelectrodes and the counter electrode; and storage capacitance formedbetween the pixel electrodes and either of the common electrodes, aplurality of the common electrodes that are connection destinations ofthe storage capacitance being connected to the pixel electrodes of aplurality of pixels belonging to one of the scanning electrodes,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(st), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

It is preferable that the second display apparatus includes a videosignal driving circuit for simultaneously applying two kinds of videosignals having different polarities to a plurality of video signalelectrodes, and applying two kinds of video signals having differentpolarities to each of the video signal electrodes in accordance with adisplay period.

Furthermore, it is preferable that the second display apparatus includesa first common electrode that is a connection destination of storagecapacitance connected to pixel electrodes of pixels belonging to a videosignal electrode to which a video signal with a first polarity isapplied among a plurality of pixels belonging to one of the scanningelectrodes, and a second common electrode that is different from thefirst common electrode and is a connection destination of the storagecapacitance connected to the pixel electrodes of the pixels belonging tothe video signal electrode to which the video signal with a secondpolarity is applied.

Furthermore, it is preferable that the second display apparatus includesa common electrode potential control circuit for applying a voltagesignal to a plurality of common electrodes and a scanning signal drivingcircuit for applying a voltage signal to a plurality of scanningelectrodes, the common electrode potential control circuit has outputpotential levels of at least two values, and the scanning signal drivingcircuit has output potential levels of at least two values.

Furthermore, it is preferable that a potential of a scanning electrodebecomes a first potential level V_(gon) when the scanning electrode isselected and becomes substantially a second potential level V_(goff)during a retention period in which the scanning electrode is notselected,

among common electrodes that are connection destinations of storagecapacitance connected to pixel electrodes of a plurality of pixelsbelonging to the scanning electrode,

a potential of the first common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal applied to avideo signal electrode corresponding to the first common electrode ispositive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

a potential of the second common electrode becomes a first potentiallevel V_(c)(+) in a case where the polarity of the video signal appliedto the video signal electrode corresponding to the second commonelectrode is positive and a second potential level V_(c)(−) in a casewhere the polarity of the video signal is negative, when the scanningelectrode is selected, and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(st)V_(cp)/2  (Formula 2)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 3))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of γ in theportion close to the feeding ends in the screen is γ(O), a value of γ inthe portion away from the feeding ends in the screen is γ(E), and avalue of γ in a portion in a middle therebetween in terms of a distanceis γ(M), γ(M) is smaller than [γ(O)+γ(E)]/2.

Furthermore, it is preferable that V_(cp) is negative.

In the second display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

among common electrodes that are connection destinations of storagecapacitance connected to pixel electrodes of a plurality of pixelsbelonging to the scanning electrodes,

a potential of the first common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal applied to avideo signal electrode corresponding to the first common electrode ispositive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

a potential of the second common electrode becomes a first potentiallevel V_(c)(+) in a case where the polarity of the video signal appliedto the video signal electrode corresponding to the second commonelectrode is positive and a second potential level V_(c)(−) in a casewhere the polarity of the video signal is negative, when the scanningelectrode is selected, and

in a case where a difference between the first potential level V_(c)(−)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

β represented byβ=α_(gd)+α_(st)(ΔV_(cc)/ΔV_(gon))  (Formula 4)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 5))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of β in theportion close to the feeding ends in the screen is β(O), a value of β inthe portion away from the feeding ends in the screen is β(E), and avalue of β in a portion in a middle therebetween in terms of a distanceis β(M), β(M) is larger than [β(O)+β(E)]/2.

Furthermore, it is preferable that ΔV_(cc) is negative.

In the second display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

among common electrodes that are connection destinations of storagecapacitance connected to pixel electrodes of a plurality of pixelsbelonging to the scanning electrodes,

a potential of the first common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal applied to avideo signal electrode corresponding to the first common electrode ispositive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

a potential of the second common electrode becomes a first potentiallevel V_(c)(+) in a case where the polarity of the video signal appliedto the video signal electrode corresponding to the second commonelectrode is positive and a second potential level V_(c)(−) in a casewhere the polarity of the video signal is negative, when the scanningelectrode is selected,

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(st)V_(cp)/2  (Formula 2)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 3))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto, and

β represented byβ=α_(gd)+α_(st)(ΔV_(cc)/ΔV_(gon))  (Formula 4)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 5))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In order to achieve the above-mentioned object, a third displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes; video signal electrodes; common electrodes; adisplay medium interposed between the pixel electrodes and the commonelectrodes; and storage capacitance formed between electrodes, otherthan the common electrodes opposing the pixel electrodes via the displaymedium and the scanning electrodes of the stage concerned, and the pixelelectrodes,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(lc), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(lc) represented byα_(gd)=C_(gd)/C_(tot), α_(lc)=C_(lc)/C_(tot)  (Formula 6)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

It is preferable that the third display apparatus includes a videosignal driving circuit for applying two kinds of video signals havingdifferent polarities to video signal electrodes in accordance with adisplay period.

Furthermore, it is preferable that the third display apparatus includesa common electrode potential control circuit for applying a voltagesignal to a plurality of common electrodes and a scanning signal drivingcircuit for applying a voltage signal to a plurality of scanningelectrodes, the common electrode potential control circuit has outputpotential levels of at least two values, and the scanning signal drivingcircuit has output potential levels of at least two values.

In the third display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

a potential of a common electrode that opposes pixel electrodes of aplurality of pixels belonging to the scanning electrode via the displaymedium becomes a first potential level V_(c)(+) in a case where apolarity of a video signal is positive and a second potential levelV_(c)(−) in a case where the polarity of the video signal is negative,when the scanning electrode is selected, and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(lc)V_(cp)/2  (Formula 7)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 8))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of γ in theportion close to the feeding ends in the screen is γ(O), a value of γ inthe portion away from the feeding ends in the screen is γ(E), and avalue of γ in a portion in a middle therebetween in terms of a distanceis γ(M), γ(M) is smaller than [γ(O)+γ(E)]/2.

Furthermore, it is preferable that V_(cp) is negative.

In the third display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

a potential of a common electrode that opposes pixel electrodes of aplurality of pixels belonging to the scanning electrodes via the displaymedium becomes a first potential level V_(c)(+) in a case where apolarity of a video signal is positive and a second potential levelV_(c)(−) in a case where the polarity of the video signal is negative,when the scanning electrode is selected, and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

β represented byβ=α_(gd)+α_(lc)(ΔV_(cc)/ΔV_(gon))  (Formula 9)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 10))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of β in theportion close to the feeding ends in the screen is β(O), a value of β inthe L portion away from the feeding ends in the screen is β(E), and avalue of β in a portion in a middle therebetween in terms of a distanceis β(M), β(M) is larger than [β(O)+β(E)]/2.

Furthermore, it is preferable that ΔV_(cc) is negative.

In the third display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

a potential of a common electrode that opposes pixel electrodes of aplurality of pixels belonging to the scanning electrode via the displaymedium becomes a first potential level V_(c)(+) in a case where apolarity of a video signal is positive and a second potential levelV_(c)(−) in a case where the polarity of the video signal is negative,when the scanning electrode is selected,

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(lc)V_(cp)/2  (Formula 7)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 8))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto, and

β represented byβ=α_(gd)+α_(lc)(ΔV_(cc)/ΔV_(gon))  (Formula 9)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(l)(−)]/2  (Formula 10))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In order to achieve the above-mentioned object, the fourth displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes; video signal electrodes; common electrodes; adisplay medium interposed between the pixel electrodes and the commonelectrodes; and storage capacitance formed between electrodes, otherthan the common electrodes opposing the pixel electrodes via the displaymedium and the scanning electrodes of the stage concerned, and the pixelelectrodes, a plurality of the common electrodes opposing the pixelelectrodes of a plurality of pixels belonging to one of the scanningelectrodes via the display medium,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(lc), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(lc) represented byα_(gd)=C_(gd)/C_(tot), α_(lc)=C_(lc)/C_(tot)  (Formula 6)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

It is preferable that the fourth display apparatus includes a videosignal driving circuit for simultaneously applying two kinds of videosignals having different polarities to a plurality of video signalelectrodes, and applying two kinds of video signals having differentpolarities to each of the video signal electrodes in accordance with adisplay period.

Furthermore, it is preferable that the fourth display apparatus includesa first common electrode that opposes, via the display medium, pixelelectrodes of pixels belonging to a video signal electrode to which avideo signal with a first polarity is applied among a plurality ofpixels belonging to one of the scanning electrodes, and a second commonelectrode that is different from the first common electrode and opposes,via the display medium, the pixel electrodes of the pixels belonging tothe video signal electrode to which the video signal with a secondpolarity is applied.

Furthermore, it is preferable that the fourth display apparatus includesa common electrode potential control circuit for applying a voltagesignal to a plurality of common electrodes and a scanning signal drivingcircuit for applying a voltage signal to a plurality of scanningelectrodes, and the common electrode potential control circuit hasoutput potential levels of at least two values, and the scanning signaldriving circuit has output potential levels of at least two values.

In the fourth display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

among common electrodes opposing pixel electrodes of a plurality ofpixels belonging to the scanning electrode via a display medium,

a potential of the first common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal applied to avideo signal electrode corresponding to the first common electrode ispositive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

a potential of the second common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of the video signal applied tothe video signal electrode corresponding to the second common electrodeis positive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected, and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(lc)V_(cp)/2  (Formula 7)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 8))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of γ in theportion close to the feeding ends in the screen is γ(O), a value of γ inthe portion away from the feeding ends in the screen is γ(E), and avalue of γ in a portion in a middle therebetween in terms of a distanceis γ(M), γ(M) is smaller than [γ(O)+γ(E)]/2.

Furthermore, it is preferable that V_(cp) is negative.

In the fourth display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

among common electrodes opposing pixel electrodes of a plurality ofpixels belonging to the scanning electrode via a display medium,

a potential of the first common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal applied to avideo signal electrode corresponding to the first common electrode ispositive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

a potential of the second common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of the video signal applied tothe video signal electrode corresponding to the second common electrodeis positive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected, and

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

β represented byβ=α_(gd)+α_(lc)(ΔV_(cc)/ΔV_(gon))  (Formula 9)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 10))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In this case, it is preferable that, assuming that a value of β in theportion close to the feeding ends in the screen is β(O), a value of β inthe portion away from the feeding ends in the screen is β(E), and avalue of β in a portion in a middle therebetween in terms of a distanceis β(M), β(M) is larger than [β(O)+β(E)]/2.

Furthermore, it is preferable that ΔV_(cc) is negative.

In the fourth display apparatus, it is preferable that a potential of ascanning electrode becomes a first potential level V_(gon) when thescanning electrode is selected and becomes substantially a secondpotential level V_(goff) during a retention period in which the scanningelectrode is not selected,

among common electrodes opposing pixel electrodes of a plurality ofpixels belonging to the scanning electrode via a display medium,

a potential of the first common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal applied to avideo signal electrode corresponding to the first common electrode ispositive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

a potential of the second common electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of the video signal applied tothe video signal electrode corresponding to the second common electrodeis positive and a second potential level V_(c)(−) in a case where thepolarity of the video signal is negative, when the scanning electrode isselected,

in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−),

γ represented byγ=α_(lc)V_(cp)/2  (Formula 7)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 8))is set to be smaller in the portion away from the feeding ends in thescreen, compared with the portion close thereto, and

β represented byβ=α_(gd)+α_(lc)(ΔV_(cc)/ΔV_(gon))  (Formula 9)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 10))is set to be larger in the portion away from the feeding ends in thescreen, compared with the portion close thereto.

In the first and second display apparatuses, the display medium isliquid crystal.

In this case, the first and second display apparatuses have aconfiguration forming a parallel plate capacitance in which a liquidcrystal layer is interposed between the pixel electrodes and the counterelectrode.

In the third and fourth display apparatuses, the display medium isliquid crystal.

In this case, the common electrodes are formed on the same substrate asthat of the pixel electrodes, and the liquid crystal is operated by anelectric field parallel to the substrate.

In the first to forth display apparatuses, it is preferable that atleast one of the capacitances forming C_(tot) includes a capacitanceformed by two conductive layers or semiconductor layers sandwiching aninsulating layer therebetween, and an overlapping area of the twoconductive layers or semiconductor layers is made different between theportion close to the feeding ends in the screen and the portion awaytherefrom, whereby α_(st) or α_(lc), and α_(gd) are allowed to havedifferent values between the portion close to the feeding ends in thescreen and the portion away therefrom.

In order to achieve the above-mentioned object, a first method fordriving a display apparatus of the present invention is a method fordriving the first or second display apparatus, wherein after a potentialis written to the pixel electrodes via the switching elements, a voltageis superimposed via C_(st) and has a value different between the portionclose to the feeding ends in the screen and the portion away therefrom.

In the first driving method, it is preferable that, when a scanningelectrode is selected, a first potential level V_(c)(+) is applied tocommon electrodes that are connection destinations of storagecapacitance connected to pixel electrodes of a plurality of pixelsbelonging to the scanning electrode in a case where a polarity of avideo signal is positive, and a second potential level V_(c)(−) isapplied thereto in a case where a polarity of the video signal isnegative.

In order to achieve the above-mentioned object, a second method fordriving a display apparatus of the present invention is a method fordriving a third or fourth display apparatus, wherein after a potentialis written to the pixel electrodes via the switching elements, a voltageis superimposed via C_(st) and has a value different between the portionclose to the feeding ends in the screen and the portion away therefrom.

In the second driving method, it is preferable that, when a scanningelectrode is selected, a first potential level V_(c)(+) is applied tocommon electrodes opposing pixel electrodes of a plurality of pixelsbelonging to the scanning electrode via a display medium in a case wherea polarity of a video signal is positive, and a second potential levelV_(c)(−) is applied thereto in a case where a polarity of the videosignal is negative.

In order to achieve the above-mentioned object, a fifth displayapparatus of the present invention conducts a display by controlling avoltage applied to a display medium with a potential of pixel electrodesand applying voltages with both positive and negative polarities to thedisplay medium,

wherein a capacitive coupling voltage is superimposed on the pixelelectrodes from electrodes other than pixel electrodes, and adistribution of the capacitive coupling voltage is made different in adisplay region between a case where a positive voltage is applied to thedisplay medium and a case where a negative voltage is applied thereto.

In the fifth display apparatus, the electrodes other than the pixelelectrodes are common electrodes.

In order to achieve the above-mentioned object, a sixth displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes, video signal electrodes; common electrodes; acounter electrode; a display medium interposed between the pixelelectrodes and the counter electrodes; and storage capacitance formedbetween the pixel electrodes and the common electrodes,

wherein a capacitive coupling voltage from the scanning electrode, and acapacitive coupling voltage from the common electrode are allowed tohave a distribution in a screen, whereby flickering and a brightnessgradient are corrected simultaneously.

In order to achieve the above-mentioned object, a seventh displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes, video signal electrodes; common electrodes; adisplay medium interposed between the pixel electrodes and the commonelectrodes; and storage capacitance formed between electrodes, otherthan the common electrodes opposing the pixel electrodes via the displaymedium and the scanning electrodes of the stage concerned, and the pixelelectrodes,

wherein a capacitive coupling voltage from the scanning electrode, and acapacitive coupling voltage from the common electrode are allowed tohave a distribution in a screen, whereby flickering and a brightnessgradient are corrected simultaneously.

In order to achieve the above-mentioned object, an eighth displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes, video signal electrodes; common electrodes; acounter electrode; a display medium interposed between the pixelelectrodes and the counter electrode; and storage capacitance formedbetween the pixel electrodes and either of the common electrodes,

wherein a plurality of the common electrodes that are connectiondestinations of the storage capacitance are connected to the pixelelectrodes of a plurality of pixels belonging to one of the scanningelectrodes.

In order to achieve the above-mentioned object, a ninth displayapparatus of the present invention, includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes, video signal electrodes; common electrodes; and adisplay medium interposed between the pixel electrodes and the commonelectrodes,

wherein a plurality of the common electrodes oppose the pixel electrodesof a plurality of pixels belonging to one of the scanning electrodes viathe display medium.

In order to achieve the above-mentioned object, a first display elementof the present invention includes: a plurality of pixel electrodesarranged in a matrix; switching elements connected thereto; scanningelectrodes; video signal electrodes; common electrodes; a counterelectrode; a display medium interposed between the pixel electrodes andthe counter electrode; and storage capacitance formed between the pixelelectrodes and the common electrodes,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(st), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

In order to achieve the above-mentioned object, a second display elementof the present invention includes: a plurality of pixel electrodesarranged in a matrix; switching elements connected thereto; scanningelectrodes; video signal electrodes; common electrodes; a counterelectrode; a display medium interposed between the pixel electrodes andthe counter electrode; and storage capacitance formed between the pixelelectrodes and either of the common electrodes, a plurality of thecommon electrodes that are connection destinations of the storagecapacitance being connected to the pixel electrodes of a plurality ofpixels belonging to one of the scanning electrodes,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(st), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

In order to achieve the above-mentioned object, a third display elementof the present invention includes: a plurality of pixel electrodesarranged in a matrix; switching elements connected thereto; scanningelectrodes; video signal electrodes; common electrodes; a display mediuminterposed between the pixel electrodes and the common electrodes; andstorage capacitance formed between electrodes, other than the commonelectrodes opposing the pixel electrodes via the display medium and thescanning electrodes of the stage concerned, and the pixel electrodes,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(lc), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(lc) represented byα_(gd)=C_(gd)/C_(tot), α_(lc)=C_(lc)/C_(tot)  (Formula 6)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

In order to achieve the above-mentioned object, a fourth display elementof the present invention includes: a plurality of pixel electrodesarranged in a matrix; switching elements connected thereto; scanningelectrodes; video signal electrodes; common electrodes; a display mediuminterposed between the pixel electrodes and the common electrodes; andstorage capacitance formed between electrodes, other than the commonelectrodes opposing the pixel electrodes via the display medium and thescanning electrodes of the stage concerned, and the pixel electrodes, aplurality of the common electrodes opposing the pixel electrodes of aplurality of pixels belonging to one of the scanning electrodes via thedisplay medium,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(lc), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

α_(gd) and α_(lc) represented byα_(gd)=C_(gd)/C_(tot), α_(lc)=C_(lc)/C_(tot)  (Formula 6)are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom.

In order to achieve the above-mentioned object, a tenth displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes; video signal electrodes; common electrodes; acounter electrode; a display medium interposed between the pixelelectrodes and the counter electrodes; and storage capacitance formedbetween the pixel electrodes and the common electrodes, the scanningelectrodes being supplied with a power only from one side of a displayregion, a potential of the common electrodes being fixed at least on aside opposite to the side where the scanning electrodes are suppliedwith a power in the display region,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(st), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

when a value of α_(gd) represented byα_(gd)=C_(gd)/C_(tot)  (Formula 101)in a portion furthest from feeding ends of the scanning electrodes in adisplay region is α_(gd)(F), there is a position where the value ofα_(gd) becomes larger than α_(gd)(F) between the portion furthest fromthe feeding ends of the scanning electrodes in the display region and aportion closest thereto.

In order to achieve the above-mentioned object, an eleventh displayapparatus of the present invention includes: a plurality of pixelelectrodes arranged in a matrix; switching elements connected thereto;scanning electrodes; video signal electrodes; common electrodes; adisplay medium interposed between the pixel electrodes and the commonelectrodes; and storage capacitance formed between electrodes, otherthan the common electrodes opposing the pixel electrodes via the displaymedium and the scanning electrodes of the stage concerned, and the pixelelectrodes, the scanning electrodes being supplied with a power onlyfrom one side of a display region, a potential of the common electrodesbeing fixed at least on a side opposite to the side where the scanningelectrodes are supplied with a power in the display region,

wherein, in a case where a scanning electrode-pixel electrodecapacitance between the pixel electrodes and the scanning electrodes isrepresented by C_(gd), a common electrode-pixel electrode capacitancebetween the pixel electrodes and the common electrodes is represented byC_(lc), and a total capacitance connected electrically to the pixelelectrodes is represented by C_(tot),

when a value of α_(gd) represented byα_(gd)=C_(gd)/C_(tot)  (Formula 101)in a portion furthest from feeding ends of the scanning electrodes in adisplay region is α_(gd)(F), there is a position where the value ofα_(gd) becomes larger than α_(gd)(F) between the portion furthest fromthe feeding ends of the scanning electrodes in the display region and aportion closest thereto.

In the first to fourth display apparatuses, it is preferable that acommon electrode potential is different between a retention period afterthe pixel electrodes are charged with a positive video signal and aretention period after the pixel electrodes are charged with a negativevideo signal.

Furthermore, in the first to fourth display apparatuses, it ispreferable that the scanning signal driving circuit conducts writing toa plurality of lines simultaneously.

In this case, the display medium is liquid crystal of an OCB mode.

Furthermore, in the first to fourth display apparatuses, it ispreferable that the scanning signal driving circuit and the commonelectrode potential control circuit are formed on the same substrate asthat of the switching elements.

Furthermore, in the first to fourth display apparatuses, it ispreferable that the display medium is composed of a medium whose opticalstate is controlled with a current and auxiliary switching elements.

In this case, the medium whose optical state is controlled with acurrent is an organic electroluminescence medium.

According to the above-mentioned configuration, flickering or abrightness gradient can be reduced substantially in an active matrixtype liquid crystal display apparatus. Furthermore, the above-mentionedconfiguration enables a pixel configuration of a dot inversion/columninversion type to be adopted, which suppresses horizontal crosstalk.

Thus, the driving voltage/power consumption of a large liquid crystaldisplay apparatus with high resolution is reduced to substantiallyenhance uniformity, so that an industrial value is very high.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows plan views of a pixel layout of a display apparatus of afirst embodiment according to the present invention.

FIG. 2 is a cross-sectional view taken along a line A-A′ in FIG. 1.

FIG. 3 is a circuit configuration diagram of the display apparatus ofthe first embodiment according to the present invention.

FIG. 4 shows plan views of a pixel layout of a display apparatus of asecond embodiment according to the present invention.

FIG. 5 is a circuit configuration diagram of the display apparatus ofthe second embodiment according to the present invention.

FIG. 6A is a waveform diagram of an odd-numbered frame, illustrating amethod of driving the display apparatus of the second embodimentaccording to the present invention by dot inversion driving.

FIG. 6B is a waveform diagram of an even-numbered frame, illustrating amethod of driving the display apparatus of the second embodimentaccording to the present invention by dot inversion driving.

FIG. 7A is a waveform diagram of an odd-numbered frame, illustrating amethod of driving the display apparatus of the second embodimentaccording to the present invention by column inversion driving.

FIG. 7B is a waveform diagram of an even-numbered frame, illustrating amethod of driving the display apparatus of the second embodimentaccording to the present invention by column inversion driving.

FIG. 8 is a circuit diagram of one pixel of a display apparatus of afourth embodiment according to the present invention.

FIG. 9 shows plan views of a pixel layout of the display apparatus ofthe fourth embodiment according to the present invention.

FIG. 10 is a cross-sectional view taken along a line A-A′ in FIG. 9.

FIG. 11 is a circuit configuration diagram of the display apparatus ofthe fourth embodiment according to the present invention.

FIG. 12 shows plan views of a pixel layout of a display apparatus of afifth embodiment according to the present invention.

FIG. 13 is a circuit configuration diagram of the display apparatus ofthe fifth embodiment according to the present invention.

FIG. 14 is a circuit diagram of one pixel of a display apparatus of theprior art and that of the first embodiment according to the presentinvention.

FIG. 15 is a waveform diagram illustrating a method for driving adisplay apparatus of the prior art and that of the first embodimentaccording to the present invention.

FIG. 16A shows a polarity pattern of pixels and a scanning signalwaveform in a field inversion system.

FIG. 16B shows a polarity pattern of pixels and a scanning signalwaveform in a line inversion system.

FIG. 16C shows a polarity pattern of pixels and a scanning signalwaveform in a column inversion system.

FIG. 16D shows a polarity pattern of pixels and a scanning signalwaveform in a dot inversion system.

FIG. 17 is a waveform diagram illustrating that a recharge voltage isdifferent between portions close to feeding ends and a portion awaytherefrom.

FIG. 18 is a view illustrating the relationship of the magnitude of arecharge voltage.

FIG. 19A shows an example of a method for providing a distribution of βin a screen.

FIG. 19B shows an example of a method for providing a distribution of βin a screen.

FIG. 19C shows an example of a method for providing a distribution of βin a screen.

FIG. 19D shows an example of a method for providing a distribution of βin a screen.

FIG. 20A shows an example of a method for providing a distribution of γin a screen.

FIG. 20B shows an example of a method for providing a distribution of γin a screen.

FIG. 20C shows an example of a method for providing a distribution of γin a screen.

FIG. 20D shows an example of a method for providing a distribution of γin a screen.

FIG. 21 is a model circuit diagram for considering the optimumdistribution of β and γ.

FIG. 22 is a circuit diagram of the model circuit in FIG. 21 on aconstituent element level.

FIG. 23 is a graph showing changes in a voltage with time at each nodalpoint in the model circuit in FIG. 21.

FIG. 24 is a graph showing a distribution of a recharge voltage in ascreen obtained by model calculation.

FIG. 25A is a graph showing another example of a method for providing adistribution of β in a screen.

FIG. 25B is a graph showing another example of a method for providing adistribution of β in a screen.

FIG. 26A is a view showing a relationship between an example of a methodfor feeding a scanning electrode and a common electrode and a rechargevoltage.

FIG. 26B is a view showing a relationship between an example of a methodfor feeding a scanning electrode and a common electrode and a rechargevoltage.

FIG. 26C is a view showing a relationship between an example of a methodfor feeding a scanning electrode and a common electrode and a rechargevoltage.

FIG. 26D is a view showing a relationship between an example of a methodfor feeding a scanning electrode and a common electrode and a rechargevoltage.

FIG. 26E is a view showing a relationship between an example of a methodfor feeding a scanning electrode and a common electrode and a rechargevoltage.

FIG. 26E′ is a view showing a relationship between an example of amethod for feeding a scanning electrode and a common electrode and arecharge voltage.

FIG. 27 is a circuit diagram of one pixel in another example of adisplay apparatus of the present invention.

FIG. 28A is a waveform diagram of an odd-numbered frame, illustrating amethod for driving a display apparatus of another embodiment accordingto the present invention.

FIG. 28B is a waveform diagram of an even-numbered frame, illustrating amethod for driving a display apparatus of another embodiment accordingto the present invention.

FIG. 29A is a waveform diagram of an odd-numbered frame, illustratinganother method for driving a display apparatus of another embodimentaccording to the present invention.

FIG. 29B is a waveform diagram of an even-numbered frame, illustratinganother method for driving a display apparatus of another embodimentaccording to the present invention.

FIG. 30 is a view illustrating a relationship in magnitude of a rechargevoltage in a p-channel TFT.

FIG. 31 is a pixel constituent diagram in the case where the presentinvention is applied to a display apparatus using an organicelectroluminescence element.

FIG. 32 is a view showing a range of Δα_(gd) and Δα_(st) capable ofreducing a brightness gradient and flickering in the case whereΔα_(gd)=α_(gd)(E)−α_(gd)(O) and Δ_(st)=α_(st)(E)−α_(st)(O).

FIG. 33A is a view showing an optimum distribution of C_(st) and C_(gd)in a display region obtained by simulation.

FIG. 33B is a view showing an optimum distribution of C_(st) and C_(gd)in a display region obtained by simulation.

FIG. 33C is a view showing an optimum distribution of C_(st) and C_(gd)in a display region obtained by simulation.

FIG. 33D is view showing an optimum distribution of C_(st) and C_(gd) ina display region obtained by simulation.

BEST MODE FOR CARRYING OUT THE INVENTION

(Analysis of the Problems of the Prior Art)

Before describing specific examples of the embodiments of the presentinvention, as described in the Background Art, the results of analyzingthe causes of the first problem in which flickering and a brightnessgradient become conspicuous along with an increase in a screen size willbe described.

Hereinafter, unless otherwise specified, it is assumed that a scanningsignal (driving signal applied to a scanning electrode) and a commonelectrode control signal are supplied from both sides of a screen.Portions close to feeding ends of scanning electrodes (and commonelectrodes) in a screen, i.e., both end portions of a screen, will bereferred to as “portions close to feeding ends”, and the center of thescreen will be referred to as “a portion away from the feeding ends”.

First, a phenomenon of a recharge that must be considered for discussingthe problem will be described.

As an example, the case will be considered where a potential is shiftedfrom V_(gon) to V_(goff) after a scanning electrode is selected in FIG.15. In the portions close to the feeding ends, a voltage is changedrapidly, whereas in the portion away from the feeding ends, a waveformis distorted due to a CR time constant of the scanning electrode, andthe movement of a potential becomes smooth (it is assumed that themovement of the potential of the scanning electrode will be completedsubstantially by the time V_(c) changes from V_(c)(±) to V_(coff)). Thewaveforms of the potential of the scanning electrode in the portionsclose to the feeding ends and the portion away therefrom are drawn asrepresented by V_(g) in FIG. 17. The potential V_(d) of a pixelelectrode is substantially equal to a video signal voltage V_(sig)(+) orV_(sig)(−) at a time of completion of charging (FIG. 17 shows the caseof V_(sig)(+)); however, the potential V_(d) of the pixel electrodefluctuates along with changes in V_(g) due to the capacitive coupling byC_(gd) of the circuit in FIG. 14. A change amount ΔV_(a) of V_(d)involved in capacitive coupling when V_(g) changes from V_(gon) toV_(goff) is represented by the following Formula (15) irrespective of adistance from the feeding ends.ΔV_(a)=−(C_(gd)/C_(tot))(V_(gon)−V_(goff))where C_(tot)=C_(gd)+C_(lc)+C_(st)  (Formula 15)

The voltage change amount ΔV_(a) will be referred to as a feedthrough.This voltage value is substantially the same value irrespective of thepolarity of a video signal.

A TFT is not turned OFF immediately when the potential of the scanningelectrode falls, and the TFT is turned OFF when the potential of thescanning electrode passes a switching threshold value (potential higherthan the potential of the video signal electrode by a threshold voltage)(the TFT is turned OFF by the time when the potential of the videosignal electrode starts shifting toward a scanning period voltage).Thus, a current flows through the TFT so as to compensate for thepotential difference between the video signal electrode-pixel electrode(source-drain of the TFT) generated due to a feedthrough during a finiteperiod (represented by T_(o) or T_(e) in FIG. 17) from a time when thescanning electrode potential starts falling to a time when the scanningelectrode potential passes the switching threshold value. Therefore, theabsolute value of an actual change amount of the pixel electrodepotential becomes smaller than |ΔV_(a)|. When the voltage differencecaused by the flow of a current through the TFT is represented byΔV_(b), the change amount of the pixel electrode potential becomesΔV_(a)+ΔV_(b). FIG. 17 also shows a state of a change in the pixelelectrode potential V_(d). The waveform of V_(g) becomes smoother withincreased distance from the feeding ends of the scanning signal drivingcircuit, and a time required for the TFT to be turned OFF becomes long.Therefore, ΔV_(b) is increased with a distance from the feeding ends. Acurrent flowing through the TFT will be referred to as a rechargecurrent, and a voltage difference ΔV_(b) caused by this will be referredto as a recharge voltage.

The above-mentioned switching threshold value becomes different betweenan even-numbered frame (the case where a video signal with a positivepolarity is charged) and an odd-numbered frame (the case where a videosignal with a negative polarity is charged). The level of the switchingthreshold value when the potential of the scanning electrode shifts fromV_(gon) to V_(goff) is drawn with respect to a positive polarity and anegative polarity as shown in FIG. 18. Based on this, regarding theportions close to the feeding ends and the portion away therefrom, atime required for the TFT to be turned OFF, i.e., a period(corresponding to To or Te) for a recharge to be generated isrepresented for each polarity as in a bar graph. The length of a bargraph substantially corresponds to the magnitude of a recharge current,i.e., the magnitude of a recharge voltage. Therefore, assuming thatrecharge voltages in the case of a positive polarity and a negativepolarity in the portions close to the feeding ends are represented byΔV_(b)(O, +) and ΔV_(b)(O), and recharge voltages in the case of apositive polarity and a negative polarity in the portion away from thefeeding ends are represented by ΔV_(b)(E, +) and ΔV_(b)(E), it isunderstood that there is the following (Formula 16) relationship.ΔV_(b)(O, +)<ΔV_(b)(E, +)ΔV_(b)(O)<ΔV_(b)(E)ΔV_(b)(O, +)−ΔV_(b)(O)>ΔV_(b)(E, +)−ΔV_(b)(E)  (Formula 16)

For the purpose of reference, although the falling waveform of thepotential of the scanning electrode is set to be the same between theeven-numbered frame and the odd-numbered frame for simplicity, thefalling waveform may not necessarily be the same. In particular,considering non-linearity (a source-drain capacitance or a gate-draincapacitance when the TFT is in an ON state becomes larger than that whenthe TFT is in an OFF state), an apparent capacitance becomes larger whenthe video signal has a negative polarity. Thus, the CR time constant ofthe falling of the potential of the scanning electrode becomes large,and falling may become slow. However, even in such a case, therelationship of (Formula 16) still holds.

Next, the relationship between flickering and a brightness gradient, anda recharge voltage will be described mathematically. V_(do)(O, +),V_(do)(O), and V_(do),(E, +), V_(do)(E) of the retention potential ofthe pixel electrode in the portions close to and the portion away fromthe feeding ends can be represented by (Formula 17) with theabove-mentioned effect of a recharge added to (Formula 12).V_(do)(O, +)=V_(sig)(+)−α_(st)ΔV_(c)(+)−α_(gd)ΔV_(gon)+ΔV_(b)(O, +)V_(do)(O)=V_(sig)(−)−α_(st)ΔV_(c)(−)−α_(gd)ΔV_(gon)+ΔV_(b)(O)V_(do)(E, +)=V_(sig)(+)−α_(st)ΔV_(c)(+)−α_(gd)ΔV_(gd)+ΔV_(b)(E, +)V_(do)(E)=V_(sig)(−)−α_(st)ΔV_(c)(−)−α_(gd)ΔV_(gon)+ΔV_(b)(E)  (Formula17)

When the DC average level V_(dc)(O) and V_(dc)(E) of the potential ofthe pixel electrode in the portions close to and the portion away fromthe feeding ends and the effective value of a voltage applied to liquidcrystal V_(eff)(O) and V_(eff)(E) are calculated in (Formula 17),(Formula 18) is obtained. $\begin{matrix}{{{{V_{dc}(O)} = {{\left\lbrack {{V_{do}\left( {O, +} \right)} + {V_{do}(O)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} + {V_{sig}( - )}} \right\rbrack/2} - {\alpha_{st}{\Delta V}_{cc}} - \quad{\alpha_{gd}{\Delta V}_{gon}} + {\left\lbrack {{{\Delta V}_{b}\left( {O, +} \right)} + {{\Delta V}_{b}(O)}} \right\rbrack/2}}}}{V_{eff}(O)} = {{\left\lbrack {{V_{do}\left( {O, +} \right)} + {V_{do}(O)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} - {V_{sig}( - )}} \right\rbrack/2} - {\alpha_{st}{{\Delta V}_{cp}/2}} + \quad{\left\lbrack {{{\Delta V}_{b}\left( {O, +} \right)} + {{\Delta V}_{b}(O)}} \right\rbrack/2}}}}{{V_{dc}(E)} = {{\left\lbrack {{V_{do}\left( {E, +} \right)} + {V_{do}(E)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} + {V_{sig}( - )}} \right\rbrack/2} - {\alpha_{st}{\Delta V}_{cc}} - \quad{\alpha_{gd}\Delta_{gon}} + {\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} + {{\Delta V}_{b}(E)}} \right\rbrack/2}}}}{{V_{eff}(E)} = {{\left\lbrack {{V_{do}\left( {E, +} \right)} - {V_{do}(E)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} - {V_{sig}( - )}} \right\rbrack/2} - {\alpha_{st}{{\Delta V}_{cp}/2}} + \quad{\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} + {{\Delta V}_{b}(E)}} \right\rbrack/2}}}}} & \left( {{Formula}\quad 18} \right)\end{matrix}$

ΔV_(cc) and V_(cp) are given by the following (Formula 19).$\begin{matrix}{{{\Delta V}_{cc} = {{\left\lbrack {{{\Delta V}_{c}( + )} + {{\Delta V}_{c}( - )}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{c}( + )} + {V_{c}( - )}} \right\rbrack/2} - V_{coff}}}}{V_{cp} = {{{{\Delta V}_{c}( + )} - {{\Delta V}_{c}( - )}}\quad = {{V_{c}( + )} - {V_{c}( - )}}}}} & \left( {{Formula}\quad 19} \right)\end{matrix}$

The DC average level V_(dc)(O) and V_(dc)(E) given by the first andthird formulae of (Formula 18) represent voltage values that eliminateflickering. More specifically, if the potential of the counter electrodeis matched with the voltage values represented by the first and thirdformulae of (Formula 18), a time average value of a voltage applied toliquid crystal becomes 0, whereby flickering is eliminated. However,because of (Formula 18) and (Formula 16), the relationship representedby the following (Formula 20) is obtained, and the DC average level hasdifferent values in a screen (the DC average level is larger in theportion away from the feeding ends than in the portions close thereto).Therefore, it is impossible to eliminate flickering simultaneouslyacross the entire screen.V_(dc)(E)−V_(dc)(O)=[ΔV_(b)(E, +)+ΔV_(b)(E)]/2−[ΔV_(b)(O,+)+ΔV_(b)(O)]/2>0  (Formula 20)

On the other hand, V_(eff) given by the second and fourth formulae of(Formula 17) corresponds to an effective value of a voltage applied toliquid crystal, and the liquid crystal exhibits a brightness(transmittance) corresponding to the effective value. However, becauseof (Formula 18) and (Formula 16), the relationship represented by thefollowing (Formula 21) is obtained, and the effective value of a voltageapplied to liquid crystal also has a distribution (gradient) (theeffective value is smaller in the portion away from the feeding endsthan in the portions close thereto) across a screen.V_(eff)(E)−V_(eff)(O)=[ΔV_(b)(E, +)−ΔV_(b)(E)]/2−[ΔV_(b)(O,+)−ΔV_(b)(O)]/2<0  (Formula 21)

The reasons for the occurrence of flickering and a brightness gradientdue to the distribution of a recharge voltage in a screen have beendescribed as above.

When a screen size becomes large, the distance from the feeding ends ofthe portion away therefrom becomes large naturally. Then, the differencein the above-mentioned recharge voltage ΔV_(b) between the portion awayfrom the feeding ends and the portions close thereto becomes large,increasing flickering and a brightness gradient.

Furthermore, in the case where the screen size is large, an influence bythe fluctuation in the potential of the common electrode is notnegligible. More specifically, when the potential of the scanningelectrode changes from V_(gon) to V_(goff), the potential of the pixelelectrode decreases due to a feedthrough. Simultaneously with this, thepotential of the common electrode also decreases due to the capacitivecoupling between the scanning electrode and the common electrode createdby C_(gd) and C_(st) in FIG. 14. The potential decrease is small in theportions close to the feeding ends of the common electrode, whereas itis large in the portion away from the feeding ends of the commonelectrode. When the potential of the common electrode decreases, thepotential of the pixel electrode further decreases along therewith.Then, compared with the case where it is assumed that the potential ofthe common electrode does not change at all, a larger recharge currentflows toward the pixel electrode. Thus, the retention potential of thepixel electrode in the portion away from the feeding ends becomes muchlarger than that in the portions close to the feeding ends, which makesthe problems such as a brightness gradient and flickering moreconspicuous.

(Description 1 of the Principle of the Present Invention: Principle of aReduction in a Brightness Gradient/Flickering)

The above-mentioned analysis was conducted, and means for eliminating abrightness gradient and flickering was found. This is the content of thepresent invention, and the values of α_(st) and α_(gd) are allowed tohave a gradient in a screen. Hereinafter, the principle thereof will bedescribed.

Now, it is assumed that α_(st) and α_(gd) are not constant in a screen(more specifically, at least one of C_(gd), C_(st), and C_(lc) is notconstant). It is assumed that α_(st) and α_(gd) in portions close to thefeeding ends are α_(st)(O) and α_(gd)(O), and α_(st) and α_(gd) in aportion away from the feeding ends are α_(st)(E) and α_(gd)(E). Herein,“O” denotes the portions close to the feeding ends, and “E” denotes aportion away from the feeding ends.

In the case where the portions close to the feeding ends and the portionaway from the feeding ends are charged positively and negatively, whenFormula 17 is applied, four formulae (Formula 22) are obtained.  (Formula 22)V_(do)(O, +)=V_(sig)(+)−α_(st)(O)ΔV_(c)(+)−α_(gd)(O)ΔV_(gon)+ΔV_(b)(O,+)V_(do)(O, −)=V_(sig)(−)−α_(st)(O)ΔV_(c)(−)−α_(gd)(O)ΔV_(gon)+ΔV_(b)(O,−)V_(do)(E, +)=V_(sig)(+)−α_(st)(E)ΔV_(c)(+)−α_(gd)(E)ΔV_(gon)+ΔV_(b)(E,+)V_(do)(E, −)=V_(sig)(−)−α_(st)(E)ΔV_(c)(−)−α_(gd)(E)ΔV_(gon)+ΔV_(b)(E,−)

Herein, for example, the notation of V_(do)(j, ±)(j=O or E) refers to anamount during positive charge (+) or negative charge (−) at a positionj(j=O→portions close to the feeding ends, j=E→portion away from thefeeding ends). This also applies to V_(sig)(±) and ΔV_(b)(j, ±).

In the case of the prior art, the value of ΔV_(b) varies between theportions close to the feeding ends and the portion away from the feedingends. Therefore, V_(do) also varies, which causes flickering and abrightness gradient. According to the present invention, by changing thetwo respective values of α_(st) and α_(gd) independently, it isattempted to correct the difference in the value of ΔV_(b). When DCaverage levels V_(dc)(O) and V_(dc)(E) and the liquid crystalapplication voltage effective value V_(eff)(O) and V_(eff)(E) arecalculated by (Formula 22) in the same way as in (Formula 17) and(Formula 18), the following (Formula 23) holds. $\begin{matrix}{{{{V_{dc}(O)} = {{\left\lbrack {{V_{do}\left( {O, +} \right)} + {V_{do}\left( {O, -} \right)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} + {V_{sig}( - )}} \right\rbrack/2} - \quad{{\alpha_{st}(O)}{\Delta V}_{cc}} - {{\alpha_{gd}(O)}{\Delta V}_{gon}} + \quad{\left\lbrack {{{\Delta V}_{b}\left( {O, +} \right)} + {{\Delta V}_{b}\left( {O, -} \right)}} \right\rbrack/2}}}}{V_{eff}(O)} = {{\left\lbrack {{V_{do}\left( {O, +} \right)} - {V_{do}\left( {O, -} \right)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} - {V_{sig}( - )}} \right\rbrack/2} - {\alpha_{st}(O)}}}}\quad{{{\Delta V}_{cp}/2} + {\left\lbrack {{{\Delta V}_{b}\left( {O, +} \right)} - {{\Delta V}_{b}\left( {O, -} \right)}} \right\rbrack/2}}{{V_{dc}(E)} = {{\left\lbrack {{V_{do}\left( {E, +} \right)} + {V_{do}\left( {E, -} \right)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} + {V_{sig}( - )}} \right\rbrack/2} - \quad{{\alpha_{st}(E)}{\Delta V}_{cc}} - {{\alpha_{gd}(E)}\Delta\quad V_{gon}} + \quad{\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} + {{\Delta V}_{b}\left( {E, -} \right)}} \right\rbrack/2}}}}{{V_{eff}(E)} = {{\left\lbrack {{V_{do}\left( {E, +} \right)} - {V_{do}\left( {E, -} \right)}} \right\rbrack/2}\quad = {{\left\lbrack {{V_{sig}( + )} - {V_{sig}( - )}} \right\rbrack/2} - {\alpha_{st}(E)}}}}\quad{{{\Delta V}_{cp}/2} + {\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} - {{\Delta V}_{b}\left( {E, -} \right)}} \right\rbrack/2}}} & \left( {{Formula}\quad 23} \right)\end{matrix}$When the difference ΔV_(eff) of the liquid crystal application voltageeffective value at the portions close to the feeding ends and theportion away from the feeding ends is calculated, (Formula 24) holds.$\begin{matrix}{{\Delta V}_{eff} = {{{V_{eff}(E)} - {V_{eff}(O)}}\quad = {{{{- \left\lbrack {{\alpha_{st}(E)} - {\alpha_{st}(O)}} \right\rbrack}{V_{cp}/2}} + {\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} - \quad{{\Delta V}_{b}\left( {E, -} \right)} - {{\Delta V}_{b}\left( {O, +} \right)} + {{\Delta V}_{b}\left( {O, -} \right)}} \right\rbrack/2}}\quad = {{- \left\lbrack {{\gamma(E)} - {\gamma(O)}} \right\rbrack} + {\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} - \quad{{\Delta V}_{b}\left( {E, -} \right)} - {{\Delta V}_{b}\left( {O, +} \right)} + {{\Delta V}_{b}\left( {O, -} \right)}} \right\rbrack/2}}}}} & \left( {{Formula}\quad 24} \right)\end{matrix}$where γ(O) and γ(E) are given by the following (Formula 25):γ(O)=α_(st)(O)V_(cp)/2γ(O)=α_(st)(E)V_(cp)/2  (Formula 25)When the difference ΔV_(dc) of the DC average levels is calculated, thefollowing (Formula 26) holds. $\begin{matrix}{\left. {{\Delta V}_{dc} = {{{V_{DC}(E)} - {V_{DC}(O)}}\quad = {{{{- \left\lbrack {{\alpha_{st}(E)} - {\alpha_{st}(O)}} \right\rbrack}V_{cc}} - {\left\lbrack {{\alpha_{gd}(E)} - \quad{\alpha_{gd}(O)}} \right\rbrack\Delta\quad V_{gon}} + {\left\lbrack {{{\Delta V}_{b}\left( {E, +} \right)} + \quad{{\Delta V}_{b}\left( {E, -} \right)} - \quad{{\Delta V}_{b}\left( {O, +} \right)} + {{\Delta V}_{b}\left( {O, -} \right)}} \right\rbrack/2}}\quad = {{{- \left\lbrack {{\beta(E)} - {\beta(O)}} \right\rbrack}\Delta\quad V_{gon}} + {{\Delta V}_{b}\left( {E, +} \right)} + \quad{{\Delta V}_{b}\left( {E, -} \right)} - {{\Delta V}_{b}\left( {O, +} \right)} - {{\Delta V}_{b}\left( {O, -} \right)}}}}} \right\rbrack/2} & \left( {{Formula}\quad 26} \right)\end{matrix}$where β(O) and β(E) are given by the following (Formula 27):β(O)=α_(gd)(O)+α_(st)(O)(ΔV_(cc)/ΔV_(gon))β(E)=α_(gd)(E)+α_(st)(E)(ΔV_(cc)/ΔV_(gon))  (Formula 27)

In order to eliminate a brightness gradient completely, ΔV_(eff)=0 onlyneeds to be satisfied in (Formula 24), and the relationship between γ(O)and γ(E) may be selected so as to satisfy the following (Formula 28):γ(E)−γ(O)=[ΔV_(b)(E, +)−ΔV_(b)(E, −)−ΔV_(b)(O, +)+ΔV_(b)(O,−)]/2  (Formula 28)

According to the third formula of (Formula 16), the right side of(Formula 28) is negative, so that the relationship between γ(O) and γ(E)may be as represented by (Formula 29).γ(O)>γ(E)  (Formula 29)

In order to eliminate flickering completely, ΔV_(dc)=0 only needs to besatisfied in (Formula 26), and the relationship between β(O) and β(E)only needs to be selected so as to satisfy the following Formula 30):[β(E)−β(O)]ΔV_(gon)=[ΔV_(b)(E, +)+ΔV_(b)(E, −)−ΔV_(b)(O, +)−ΔV_(b)(O,−)]/2  (Formula 30)

According to the first and second formulae of (Formula 16), the rightside of (Formula 28) is positive, and ΔV_(gon) also is positive.Therefore, the relationship between β(O) and β(E) only needs to satisfythe following (Formula 31):β(O)<β(E)  (Formula 31)

By selecting γ and β conveniently as described above, flickering and abrightness gradient can be eliminated.

In summary, the conditions for eliminating a brightness gradient andflickering with an array configuration as shown in FIG. 14 can bedescribed as follows:

[1] Necessary conditions for eliminating a brightness gradient:

The value of γ is smaller in the portion away from the feeding ends in ascreen, compared with the portions close thereto.

[2] Necessary conditions for eliminating flickering]

The value of β is larger in the portion away from the feeding ends in ascreen, compared with the portions close thereto.

In the above, suffixes O and E are omitted.

It may be possible that only the necessary conditions [1] are satisfied,and the necessary conditions [2] are not satisfied. In the case of thisconfiguration, although a brightness gradient is eliminated, flickeringis not eliminated. As a method for eliminating flickering actively underthese conditions, it is considered to correct ahead of time the videosignal generated in a video signal driving circuit. This means that anexcess signal processing circuit is added, which increases cost.

In contrast, it also may be possible that only the necessary conditions[2] are satisfied and the necessary conditions [1] are not satisfied. Inthe case of this configuration, although flickering is eliminated, abrightness gradient is not eliminated. As a method for eliminating abrightness gradient actively under these conditions, it is considered tocorrect ahead of time a video signal generated in a video signal drivingsignal. This case also means that an excess signal processing circuit isadded, which increases cost.

Most desirably, both the necessary conditions [1] and [2] are satisfied.In this case, a video of high quality without flickering and abrightness gradient can be obtained without adding an excess signalprocessing circuit for correcting a video signal ahead of time, so thatboth low cost and high quality can be satisfied.

In the case where β and γ (or α_(st) and α_(gd)) are set to be differentvalues between the portions close to the feeding ends and the portionaway therefrom, it is required to change these values independently.Therefore, it is desirable that α_(st) and α_(gd) are varied by settingat least two of capacitance values C_(st), C_(gd), and C_(lc), (in otherwords, capacitance values constituting C_(tot)) contributing to α_(st)and α_(gd) between the portions close to the feeding ends and theportion away therefrom.

Actually, for example, in the case where C_(gd) and C_(lc) are set to beconstant, and only C_(st) is set to have different values between theportions close to the feeding ends (the value of C_(st) is assumed to beC_(st)(O)) and the portion away therefrom (the value of C_(st) isassumed to be C_(st)(E)) to satisfy C_(st)(O)<C_(st)(E),α_(gd)(O)>α_(gd)(E) and α_(st)(O)<α_(st)(E) are satisfied according to(Formula 14). Under this condition, in the case where V_(cp)<0 andΔV_(cc)<0 (it will be described later as a supplement that theseconditions are desirable), γ(O)>γ(E) is obtained from (Formula 25), andβ(O)>β(E) is obtained from (Formula 27). In this case, although (Formula29) is satisfied, (Formula 31) is not satisfied. Thus, although abrightness gradient reduction effect is obtained, a flickering reductioneffect cannot be obtained.

In contrast, in the case of C_(st)(O)>C_(st)(E), the relationshipsγ(O)<γ(E) and β(O)<β(E) are obtained. More specifically, although(Formula 31) is satisfied, (Formula 29) is not satisfied. Thus, althougha flickering reduction effect is obtained, a brightness gradientreduction effect cannot be obtained. Furthermore, this also applies to,for example, the case where C_(st) and C_(lc) are set to be constant,and only C_(gd) is varied. There is no problem when C_(st) and C_(gd)are set to be constant, and only C_(lc) is varied.

A more detailed description will be provided regarding the above. Now,assuming that Δα_(gd)=α_(gd)(E)−α_(gd)(O), andΔα_(st)=α_(st)(E)−α_(st)(O), the range of Δα_(gd) and Δα_(st) satisfyingboth (Formula 29) and (Formula 31) can be represented by a hatchedportion in FIG. 32 (assuming the case of V_(cp)<0, ΔV_(cc)<0). Incontrast, in the case where C_(gd) and C_(lc) are set to be constant,and only C_(st) is varied between the portion away from the feeding endsand the portions close thereto (C_(st)(O)≠C_(st)(E)), Δα_(gd) andΔα_(st) can be represented by (Formula 46). $\begin{matrix}\left. {\left. {{\Delta\alpha}_{gd} = {{{\alpha_{gd}(E)} - {\alpha_{gd}(O)}}\quad = {{{C_{gd}/\left( {C_{gd} + C_{lc} + {C_{st}(E)}} \right)} - \quad{C_{gd}/\left( {C_{gd} + C_{lc} + {C_{st}(O)}} \right)}}\quad = {{{- {C_{gd}\left\lbrack {{C_{st}(E)} - {C_{st}(O)}} \right\rbrack}}/\left\lbrack {C_{gd} + \quad C_{lc} + {C_{st}(E)}} \right)}\left( {C_{gd} + C_{lc} + {C_{st}(O)}} \right)}}}} \right\rbrack{{\Delta\alpha}_{st} = {{{\alpha_{st}(E)} - {\alpha_{st}(O)}}\quad = {{{{C_{st}(E)}/\left( {C_{gd} + C_{lc} + {C_{st}(E)}} \right)} - \quad{{C_{st}(O)}/\left( {C_{gd} + C_{lc} + {C_{st}(O)}} \right)}}\quad = {{{\left( {C_{gd} + C_{lc}} \right)\left\lbrack {{C_{st}(E)} - {C_{st}(O)}} \right\rbrack}/\left\lbrack {C_{gd} + \quad C_{lc} + {C_{st}(E)}} \right)}\left( {C_{gd} + C_{lc} + {C_{st}(O)}} \right)}}}}} \right\rbrack & \left( {{Formula}\quad 46} \right)\end{matrix}$

Thus, it is understood that there is a relationship of (Formula 47)between Δα_(gd) and Δα_(st).Δα_(gd)/Δα_(st)=−C_(gd)/(C_(gd)+C_(lc))  (Formula 47)

Furthermore, in the case where C_(st) and C_(lc) are set to be constant,and only C_(gd) is varied between the portion away from the feeding endsand the portions away therefrom (C_(gd)(O)≠C_(gd)(E)), a relationship of(Formula 48) can be obtained similarly.Δα_(gd)/Δα_(st)=−C_(st)/(C_(st)+C_(lc))  (Formula 48)

The right sides of (Formula 47) and (Formula 48) have negative values.Therefore, when these relationships are added to FIG. 32, a straightline passing through an origin and having a negative slope can beobtained (excluding an origin) in both cases. Therefore, the straightline of (Formula 47) or (Formula 47) does not have a portion in commonwith the hatched region. More specifically, this shows that in the caseof varying only C_(st) or only C_(gd), both a flickering reductioneffect and a brightness gradient reduction effect cannot be satisfied.

(Principle 2 of the Present Invention: Optimum Distribution of β and γ)

The portions close to the feeding ends and the portion away therefromhave been used as representative points in the above. However, variouschange patterns of γ and β can be considered at each position across ascreen. FIG. 19 shows some examples regarding β, and FIG. 20 shows someexamples regarding γ. In each graph, the horizontal axis represents ahorizontal position in a screen, and the vertical axis represents avalue of β or γ. O, E, and M on the horizontal axis represent a portionclose to the feeding ends, a portion away from the feeding ends, and aportion in the middle therebetween in terms of distance, respectively.As shown in FIG. 19A or 20A, a pattern that changes linearly can beconsidered most easily. Furthermore, as shown in FIG. 19B or 20B, anon-linear change also may be considered. Alternatively, as shown inFIG. 19C or 20C, a change in stages also may be considered.Alternatively, as shown in FIG. 19D or 20D, a combination of a constantportion and a portion with a slope also may be considered. In any case,the values of β and γ in the portion close to the feeding ends and inthe portion away from the feeding ends satisfy (Formula 31) and (Formula29). Thus, in any case, the effects of the present invention can beobtained.

In particular, as shown in FIGS. 19B, 19D, 20B, and 20D, it is desirablethat β represents an upward convex trend between the portion close tothe feeding ends and the portion away therefrom, and γ represents adownward convex trend between the portion close to the feeding ends andthe portion away therefrom. The reason for this will be described below.

Scanning electrodes can be considered as wires having an RC distributioncircuit constant. FIG. 21 shows scanning electrodes schematically, using5-stage RC circuits, where the total capacitance between the portionclose to the feeding ends and the portion away therefrom is representedas C, and the resistance thereof is represented as R. This assumes thata region between the portion close to the feeding ends of the scanningelectrodes and the portion away therefrom is divided equally into fivesections, and each of the sections represented by a unit RC circuit asshown in FIG. 22 is connected to each other. Assuming that the lengthbetween the portion close to the feeding ends of the scanning electrodesand the portion away therefrom is L, node potentials V_(g)O, V_(g) 1,V_(g) 2, V_(g) 3, V_(g) 4, V_(g) 5, from the feeding ends of 0 (portionclose to the feeding ends), L/10, 3L/10, L/2, 7L/10, 9L/10, and L(portion away from the feeding ends). The portion close to the feedingends is supplied with a voltage by a scanning signal driving circuit. InFIG. 21, V_(g)O is a supply voltage of the scanning signal drivingcircuit, and R_(g) is an internal impedance of the scanning signaldriving circuit.

FIGS. 19 and 20 show the case assuming that a voltage is supplied fromboth sides. Since the graphs in FIGS. 19 and 20 are symmetrical, onlythe left half or right half may be considered. In the case of thecircuit model in FIG. 21, only the left half of FIG. 19 or 20 isconsidered.

A change with time in each node potential when the potential of thescanning electrodes in the above-mentioned circuit falls (i.e., whenV_(g)O changes in the form of steps from an ON-level V_(gon) to anOFF-level V_(goff)) can be solved by a circuit equation. FIG. 23 showsthe results obtained by actually conducting calculation of numericalvalues. Herein, it is assumed that the potential of the scanningelectrodes V_(g) 0 shifts from V_(gon) to V_(goff) at a time t=0, and asan example, calculation is conducted with respect to the case ofR_(g)=R/9, V_(gon)=25 V, and V_(goff)=0 V. The horizontal axis isnormalized with CR.

Next, as in the prior art, assuming that the capacitance of C_(gd),C_(st), C_(lc), and the like are constant irrespective of a position,how ΔV_(b) changes with a position will be considered. The pixelconfiguration at each point is shown by the circuit in FIG. 14, so thata change with time in a pixel electrode potential V_(d) when theabove-mentioned V_(g)O, V_(g) 1, v_(g) 2, . . . are applied as V_(g)(n)only needs to be tracked. When V_(c)(n), V_(f), and V_(s) are assumed tobe constant potentials in such a circuit, a change with time in V_(d) isrepresented by (Formula 32).I_(ds)+C_(tot)·dV_(d)/dt−C_(gd)·dV_(g)(n)/dt=0  (Formula 32)Herein, C_(tot)=C_(gd)+C_(gs)+C_(lc). Furthermore, I_(ds) is asource-drain current of a TFT, which is represented by (Formula 33) whenideal MOS characteristics are assumed.I_(ds)=k[{V_(g)(n)−V_(s)−V_(t)}²−{V_(g)(n)−V_(d)−V_(t)}²]  (Formula 33)(where V_(g)(n)−V_(s)≧V_(t), V_(g)(n)−V_(d)≧V_(t))I_(ds)=k{V_(g)(n)−V_(s)−V_(t)}²(where V_(g)(n)−V_(s)≧V_(t), V_(g)(n)−V_(d)<V_(t))I_(ds)=−k{V_(g)(n)−V_(d)−V_(t)}²(where V_(g)(n)−V_(s)<V_(t), V_(g)(n)−V_(d)≧V_(t))I_(ds)=0(where V_(g)(n)−V_(s)<V_(t), V_(g)(n)−V_(d)<V_(t))Herein, k is a constant representing a charge ability of a TFT, andV_(t) represents a threshold voltage of a TFT. The initial conditions of(Formula 32) are V_(d)=V_(s), V_(g)(n)=V_(gon) at t=0. Furthermore,after a sufficient time elapses (t=∞), V_(g)(n)=V_(goff), a TFT is in anOFF state, and I_(ds)=0 (in the case of the fourth formula of (Formula33)). Therefore, V_(d) becomes a constant value (dV_(d)/dt=0(t=∞) isobtained from (Formula 32)). The difference between the value of a finalplateau V_(do) of V_(d) obtained by numerical calculation and the valueof a final plateau V_(do) of V_(d) in the absence of recharge, i.e., thevalue of V_(do) when I_(ds)=0 always is satisfied in (Formula 32), i.e.,V_(do)=V_(s)−(C_(gd)/C_(tot))(V_(gon)−V_(goff)), corresponds to arecharge voltage ΔV_(b). FIG. 24 shows the results obtained by actuallycalculating the value of ΔV_(b), assuming that V_(t)=2 V, V_(s)=6V_(gd)/C_(tot)=0.05, and k=b 6×10⁻⁹ A/V², as an example. In this graph,a horizontal axis shows values normalized assuming that the portionclose to the feeding ends is “0”, and the portion away from the feedingends is “1”. A vertical axis also shows values normalized assuming thatΔV_(b) at the portion away from the feeding ends is “1” . As isunderstood from this graph, a distribution of a recharge voltage has anupward convex shape.

When there is such a distribution of a recharge voltage, thedistribution of a DC average level of a pixel electrode and a liquidcrystal application voltage effective value generated by thedistribution of the recharge voltage also has a shape as shown in FIG.24 (in the liquid crystal application voltage effective value, as ispresumed from the fact that the right side of (Formula 21) becomesnegative, a graph of FIG. 24 inverted upside down can be obtained. Inthe DC average level, the right side of (Formula 20) is positive, sothat a graph is not inverted upside down). Thus, it is desirable thatthe distributions of β and γ for correcting flickering (caused by thedistribution of a DC average level) and a brightness gradient (caused bythe distribution of a liquid crystal application voltage effectivevalue) has a shape similar to that in FIG. 24. More specifically, it isdesirable that β is set to be as shown in FIG. 19B, and γ is set to beas shown in FIG. 20B (FIGS. 19D and 20D may be possible).

The above description will be considered paying attention to a position(hereinafter, simply referred to as an intermediate position) in themiddle in terms of a distance between the portion close to the feedingends and the portion away therefrom. Assuming that values of β and γ atthe portion close to the feeding ends are β(O) and γ(O), the valuesthereof at the portion away from the feeding ends are β(E) and γ(E), andthe values thereof at an intermediate position are β(M) and γ(M), asshown in FIGS. 19A and 20A, the values of β and γ at the intermediateposition in the case where a linear slope is provided are given byβ(M)=[β(O)+β(E)]/2 and γ(M)=[γ(O)+γ(E)]/2. Compared with this, in thecase where the effects of reduction of flickering and a brightnessgradient are obtained effectively, i.e., in the case as shown in FIGS.19B, 20B, 19D, and 20D, the following relationship of (Formula 34) issatisfied.β(M)>[β(O)+β(E)]/2γ(M)<[γ(O)+γ(E)]/2  (Formula 34)

The first formula of (Formula 34) is a conditional expression regardingflickering, and the second formula is a conditional expression regardinga brightness gradient.

If only (Formula 34) is satisfied when (Formula 29) and (Formula 31) aresatisfied, the above-mentioned effects of a reduction in flickering anda brightness gradient can be obtained sufficiently. For example, asshown in FIGS. 25A and 25B, β may not always increase monotonically withrespect to a distance from the feeding ends, and in a more extreme case,as shown in FIG. 25A, β(M) may exceed β(E). However, even in thesecases, the effects of a reduction in flickering and a brightnessgradient can be obtained. This also applies to γ.

(Supplementary Item 1 Regarding the Principle: V_(cp) and ΔV_(cc))

A supplementary description will be made with respect to V_(cp) of(Formula 19). If the third term regarding recharge is ignored since itis very small, and α_(st)V_(cp) is assumed to be negative in the formularegarding V_(eff) of (Formula 18) and (Formula 23), an effective valueof a voltage applied to liquid crystal becomes a value larger than avideo signal amplitude [V_(sig)(+)−V_(sig)(−)]/2. This corresponds tothe following: an advantage in which a voltage (e.g., 10 to 15 V) equalto or higher than a withstand voltage can be applied to liquid crystal,using a video signal driving IC with a low withstand voltage (e.g.,about 5 V), as described in the Background Art. Therefore, it isdesirable that α_(st)V_(cp) is negative. Since α_(st) is a capacitanceratio and is always positive, it is desirable that V_(cp) is negative.

Furthermore, a supplementary description will be made with respect toΔV_(cc) c of (Formula 19). If the third term regarding recharge isignored since it is very small in (Formula 18) and (Formula 23)regarding V_(dc), by satisfying the following (Formula 35), a DC averagelevel [V_(sig)(+)+V_(sig(−)]/)2 of a video signal can be matched with aDC average level V_(dc)(O) or V_(dc)(E) of a pixel electrode.ΔV_(cc)=−(α_(gd)/α_(st))ΔV_(gon)  (Formula 35)Because of the above, a d.c. voltage component is not supplied between avideo signal electrode and a pixel electrode, and unnecessary ions canbe suppressed from being generated in liquid crystal and an insulatingfilm. Therefore, stability with time can be enhanced. Since ΔV_(gon),α_(gd), and α_(st) are positive, it is desirable that ΔV_(cc) isnegative. Even if (Formula 35) is not satisfied, if at least ΔV_(cc) isnegative, a voltage difference between a DC average level[V_(sig)(+)+V_(sig)(−)]/2 of a video signal and a DC average levelV_(dc)(O) or V_(dc)(E) of a pixel electrode can be reduced, and theabove-mentioned effects can be obtained to some degree.(Supplementary Item 2 Regarding the Principle: Method for Supplying APower of Scanning Electrodes and Common Electrodes)

Next, a supplementary description will be made with respect to a methodfor supplying a power of scanning electrodes and common electrodes. In(analysis of the problems of the prior art), it is described that arecharge current (recharge voltage) increases due to the fluctuation ina potential of common electrodes. It also is described that thisinfluence is small in the portions close to the feeding ends of thecommon electrodes, whereas it is large in the portion away from thefeeding ends. Thus, the in-plane distribution of a recharge voltagedepends slightly on a method for supplying a power of the commonelectrodes, as well as a method for supplying a power of the scanningelectrodes. Now, for example, the following five combinations of methodsfor supplying power by the scanning electrodes and the common electrodesare considered.

(A) The scanning electrodes and the common electrodes supply power fromboth sides (in the above description, this case is assumed).

(B) The scanning electrodes supply power from both sides, and the commonelectrodes supply a power from one side.

(C) The scanning electrodes supply power from one side, and the commonelectrodes supply a power from both sides.

(D) The scanning electrodes and the common electrodes supply power fromone side (from the same side).

(E) The scanning electrodes and the common electrodes supply power fromone side (from different sides).

(In addition, for example, power may be supplied alternately from bothsides of every other line, and power may be supplied from the left sidein the upper half of a screen and from the right side in the lower halfthereof. These cases are applicable to any of the above-mentioned (A) to(E), if one line is considered.)

Regarding the above-mentioned (A) to (E), FIGS. 26A to 26E show apredicted in-plane distribution (distribution in a horizontal direction)representing how a recharge voltage ΔV_(b) is generated. In thesefigures, G represents a scanning electrode, and C represents a commonelectrode. A portion with a square mark (□) represents a feeding end. Acurve represented by a broken line shows a recharge voltage in the casewhere fluctuations in a potential of the common electrode are notconsidered, and a curve represented by a solid line shows a rechargevoltage in the case where fluctuations in a potential of the commonelectrode are considered. In the case where the fluctuations in apotential of the common electrode are not considered, a recharge voltageexhibits an arched curve when the scanning electrode is supplied with apower from both sides ((A), (B)), and exhibits a semi-arched curve whenthe scanning electrode is supplied with a power from one side ((C), (D),(E)). When the fluctuations in a potential of the common electrode areconsidered, ΔV_(b) is loaded by the corresponding amount. The loadedamount at this time becomes small at the portion close to the feedingends of the common electrode, and becomes large at the portion away fromthe feeding ends. In the case of (E), due to the ΔV_(b) distributiongenerated only by the scanning electrode and the amount loaded dependingupon the effect of fluctuations in a potential of the common electrode,as shown in FIG. 26E, there may be the case in which ΔVb is smaller inthe feeding ends of the scanning electrode, compared with the feedingends of the common electrode, and the case in which ΔVb is smaller inthe feeding ends of the common electrode, compared with the feeding endsof the scanning electrode as shown in FIG. 26E′.

In order to obtain the effect of reduction in a brightness gradient andflickering according to the present invention most effectively, it ismost desirable to provide a distribution to β and γ (more exactly, |γ|)in accordance with the shape of ΔV_(b) in FIGS. 26A to 26E (morespecifically, so that a brightness gradient and flickering generated byΔV_(b) are corrected). However, it is not necessarily required toprovide such a distribution over the entire screen.

Hereinafter, regarding each case of (A) to (E), the relationship withrespect to the expression of the present invention will be described.First, in (A) to (E), end portions of a screen to which at least one ofa scanning electrode and a common electrode is supplied with a powerwill be referred to as “portions close to the feeding ends). Morespecifically, in all the cases excluding (D), both ends of the screenbecome “portions close to the feeding ends” (represented by a mark “O”in FIG. 26). In only (D), only one end portion becomes a “portion closeto the feeding ends”. In the cases other than (D), the vicinity of thecenter of the screen will be referred to as a “portion away from thefeeding ends (represented by a mark “E”). In the case of (D), the endportion not supplied with a power becomes a “portion away from thefeeding ends”. The position represented by a mark “M” in the figure is aportion corresponding to the middle between the “portion close to thefeeding ends” and the “portion away from the feeding ends” in terms of adistance.

In the cases other than (D), there are two “portions close to thefeeding ends”. When a certain value (α_(gd), α_(st), etc.) has differentvalues between the portion close to the feeding ends and the portionaway from the feeding ends, this means that a value of at least one of aplurality of “portions close to the feeding ends” is different from avalue of a “portion away from the feeding ends”. Furthermore, when acertain value (β, γ, etc.) is “larger (smaller) in a portion away fromthe feeding ends, compared with the portions dose to the feeding ends”,this means that a value of the “portion away from the feeding ends” islarger (smaller) than the value of at least one of a plurality of“portions close to the feeding ends”.

Based on the above-mentioned interpretation, it is understood from FIGS.26A to 26E′ that the relationship of (Formula 16) holds in any case.Therefore, what is described in (Description 1 of the principle of thepresent invention: Principle of a reduction in a brightnessgradient/flickering) is fully applicable.

The first and second formulae of (Formula 16) can be understood easilyif V_(b)(O, +), V_(b)(O, −), and V_(b)(E, +), V_(b)(E, −) are replacedby V_(b) in FIGS. 26A to 26 E′. Regarding the third formula, as isunderstood from FIG. 18, if it is considered that a recharge voltage ismuch larger in the case of negative charge than in the case of positivecharge, a magnitude correlation between V_(b)(O, +)−V_(b)(O, −) andV_(b)(E, +)−V_(b)(E, −) may be considered to be the same as that between−V_(b)(O, −) and −V_(b)(E, −). It is considered that the third formulaalso holds since the second formula holds.

Furthermore, curves of ΔV_(b) in FIGS. 26A to 26E′ have an upward convexshape. Therefore, what is described in (Principle 2 of the presentinvention: Optimum distribution of β and γ) is fully applicable.

(Supplementary Item 3 Regarding the Principle: Another CircuitConfiguration)

The above description is predicated on each pixel having theconfiguration in FIG. 14. However, the storage capacitance of each pixelalso is connected to wiring other than a common electrode. For example,as shown in FIG. 27, the storage capacitance may be connected to ascanning electrode (in this figure, an example of the previous stage)other than the stage concerned. In this case, if the potential of ascanning electrode of the previous stage is V_(g)(n−1), and storagecapacitance connected thereto is C_(st) 2, the formula of conservationof charge corresponding to (Formula 11) is given by (Formula 36).C_(gd)(V_(sig)(−)−V_(gon))+C_(st)(V_(sig)(−)−V_(c)(−))+  (Formula 36)C_(lc)(V_(sig)(−)−V_(f))+C_(st)2(V_(sig)(−)−V_(goff))=C_(gd)(V_(do)(−)−V_(goff))+C_(st)(V_(do)(−)−V_(coff))+C_(lc)(V_(do)(−)−V_(f))+C_(st)2(V_(do)(−)−V_(goff))C_(gd)(V_(sig)(+)−V_(gon))+C_(st)(V_(sig)(+)−V_(c)(+))+C_(lc)(V_(sig)(+)−V_(f))+C_(st)2(V_(sig)(+)−V_(goff))=C_(gd)(V_(do)(+)−V_(goff))+C_(st)(V_(do)(+)−V_(coff))+C_(lc)(V_(do)(+)−V_(f))+C_(st)2(V_(do)(+)−V_(goff))Herein, when a scanning electrode V_(g)(n) is selected, V_(g)(n−1) hasalready been selected. Therefore, the potential is V_(goff). When(Formula 36) is modified, (Formula 37) is obtained.V_(do)(−)=V_(sig)(−)−α_(st)ΔV_(c)(−)−α_(gd)ΔV_(gon)V_(do)(+)=V_(sig)(+)−α_(st)ΔV_(c)(+)−α_(gd)ΔV_(gon)  (Formula 37)Herein, ΔV_(gon), ΔV_(c)(+), and ΔV_(c)(−) are represented by (Formula13), and α_(gd) and α_(st) are represented by the following (Formula38):α_(gd)=C_(gd)/C_(tot)α_(st)=C_(st)/C_(tot)C_(tot)=C_(gd)+C_(lc)+C_(st)+C_(st) 2  (Formula 38)When the above-mentioned results are compared with Formulae 12 to 14 inthe circuit of FIG. 14, there is only a difference in that C_(st) 2 isadded to the formula of C_(tot). Therefore, as long as consideration isgiven to the fact that C_(tot) is different, the principle andsupplementary items of the present invention described in the above arefully applicable.

Depending upon the case, the following also may be considered: thevalues of α_(st) and α_(gd) are made different by making the value ofC_(st) 2 different between the portion close to the feeding ends and theportion away from the feeding ends, whereby the effects of the presentinvention are obtained.

Even if the connection destination of C_(st) 2 is a scanning electrodein the previous stage, that in a second from the previous stage, that ina third from the previous stage, that in a second from the subsequentstage, that in a third from the subsequent stage, or the like, the sameeffects can be obtained.

If C_(tot) is further generalized and considered to be a “total of theentire capacitance connected electrically to pixel electrodes”,including FIGS. 14 and 27, the description and supplementary itemsregarding the principle of the present invention are all applicable.

Hereinafter, a display apparatus constituted by using theabove-mentioned principle will be described with reference to thedrawings.

(Embodiment 1)

FIG. 1 is a plan view showing a pixel layout of a display apparatus ofthe first embodiment according to the present invention. FIG. 2 is across-sectional view taken along a line A-A′ in FIG. 1.

In FIGS. 1 and 2, reference numerals 11 and 12 denote substrates made ofglass or the like. Reference numeral 11 denotes an array substrate onwhich thin film transistors 3 (also called TFTs or switching elements)and electrodes connected thereto are formed, and reference numeral 12denotes a counter substrate opposing the array substrate. Liquid crystal13 is interposed between two substrates as a display medium, and bothends of the substrates are sealed with a seal 17. Reference numerals 14and 15 denote polarizing plates for conducting a polarization display,and 19 denotes a color filter for conducting a color display. Althoughthe color filter 19 is formed on the counter substrate 12 side, it maybe formed on the array substrate 11 side.

Scanning electrodes 1 and common electrodes 4 are formed of a firstconductive layer on the array substrate 11, and an insulating film 18covers these electrodes. A pixel electrode 5 is formed of a secondconductive layer on the insulating film 18. As shown in FIG. 2, a partof the pixel electrode overlaps the common electrode 4. An overlappingportion with the common electrode 4 constitutes a storage capacitor 7(i.e., common electrode-pixel electrode capacitance C_(st)).Furthermore, an overlapping portion of the pixel electrode 5 and thescanning electrode 1 constitutes a scanning electrode-pixel electrodecapacitance C_(gd).

As shown in FIG. 2, a transparent electrode 20 is formed on the countersubstrate 12. The transparent electrode 20 and the pixel electrode 5oppose each other via liquid crystal 13 as a display medium, therebyforming a liquid crystal capacitance C_(lc). Herein, it is assumed thatliquid crystal is TN (twisted nematic) liquid crystal.

The thin film transistor 3 is composed of a semiconductor portion 9 andthree electrodes. Gate electrodes are connected to the scanningelectrodes 1, source electrodes are connected to video signal electrodes2, and drain electrodes are connected to pixel electrodes 5.

FIG. 3 is a circuit configuration diagram of a display apparatus of thefirst embodiment according to the present invention. There are provideda common electrode-pixel electrode capacitance C_(st), a scanningelectrode-pixel electrode capacitance C_(gd), and a liquid crystalcapacitance C_(lc) in one pixel so as to correspond to FIGS. 1 and 2.When one pixel alone is considered, the circuit configuration in FIG. 3is the same as that in FIG. 14. Such pixels are arranged in a matrix,whereby a display apparatus is constituted. Furthermore, in the displayapparatus, the video signal electrodes 2 are connected to a video signaldriving circuit 22, the scanning electrodes 1 are connected to thescanning signal driving circuit 21, and the common electrodes 4 areconnected to a common electrode potential control circuit 26. Referencenumeral 23 denotes a display element excluding the driving circuits.

In FIG. 3, portions close to feeding ends and a portion away from thefeeding ends are shown. A pixel layout in each portion is as shown inFIG. 1. The display apparatus of the present embodiment is characterizedin that C_(st) and C_(gd) have different shapes between the portionclose to the feeding ends and the portion away therefrom, and acapacitance value itself also is different (area of the capacitor isdifferent). Because of this, as described in (Description 1 of theprinciple of the present invention: Principle of a reduction in abrightness gradient/flickering), a brightness gradient and flickeringcan be reduced.

The effects of the present invention can be obtained most conspicuouslywhen the following three conditions are satisfied:

(1) The video signal driving circuit is capable of applying two kinds ofvideo signals with different polarities (i.e., positive and negativevideo signals based on the potential of the counter electrode,corresponding to V_(sig)(+) and V_(sig)(−) in FIG. 15) to video signalelectrodes in accordance with a display period.

(2) The scanning signal driving circuit is capable of applying an outputpotential level with at least two values (V_(gon) and V_(goff) in FIG.15).

(3) The common electrode potential control circuit is capable ofapplying an output potential level with at least two values (V_(c)(+)and V_(c)(−) in FIG. 15).

In (FIG. 1), C_(gd)(O)<C_(gd)(E), C_(st)(O)<C_(st)(E) (this relationshipis obtained from the relationship in magnitude of an area of anoverlapping portion). However, as an example, assuming thatC_(gd)(O)=0.020 pF, C_(st)(O)=0.100 pF, C_(lc)(O)=0.100 pF,C_(gd)(E)=0.030 pF, C_(st)(E)=0.130 pF, and C_(lc)(E)=0.100 pF, theabove-mentioned conditions can be satisfied (the capacitance may becalculated from an area, a film thickness, and a dielectric constant, ormay be obtained by actual measurement).

In this case, when α_(gd)(O), α_(st)(O), and α_(gd)(E), α_(st)(E) arecalculated by (Formula 14), α_(gd)(O)=0.091, α_(st)(O)=0.455,α_(gd)(E)=0.115, α_(st)(E)=0.500. Assuming that driving conditions areΔV_(gon)=20 V, ΔV_(cc)=−3 V, and V_(cp)=−10 V, γ(O), γ(E), and β(O),β(E) are obtained by (Formula 25) and (Formula 27), and γ(O)=−2.275 V,γ(E)=−2.5 V, and β(O)=0.023, β(E)=0.040 are obtained, respectively. Morespecifically, it is understood that (Formula 29) and (Formula 31) aresatisfied, and the effect of reduction in a brightness gradient andflickering can be obtained.

Needless to say, what is described in (Principle 2 of the presentinvention: Optimum distribution of β and γ), (Supplementary item 1regarding the principle: V_(cp) and ΔV_(cc)), (Supplementary item 2regarding the principle: method for supplying a power of scanningelectrodes and common electrodes), and (Supplementary item 3 regardingthe principle: Another circuit configuration), as well as ((Description1 of the principle of the present invention: Principle of a reduction ina brightness gradient/flickering) is all applicable.

For reference, the results obtained from simulation conducted byapplying specific numerical values to parameters such as a capacitancein the present embodiment are shown in FIGS. 33A to 33D. In thissimulation, an equivalent circuit of the entire display region iscomposed with a circuit simulator, and a DC average level (V_(dc)) and aliquid crystal application voltage effective value (V_(eff)) at eachposition in the display region are calculated. The driving voltageconditions are V_(gon)=10 V, V_(goff)=−15 V, ΔV_(c)(+)=−7.5 V,ΔV_(c)(−)=2.5 V, V_(sig)(+)=2.5 V, V_(sig)(−)=−2.5 V (therefore,V_(cp)<0, ΔV_(cc)<0 are satisfied), and it is assumed that a power issupplied only from the left side of a display region in both thescanning signal driving circuit and the common electrode potentialcontrol circuit.

First, a curve marked with “no capacitance gradient” in each figurerepresents calculated results in the case where a distribution in adisplay region is not given to C_(st), C_(gd), or C_(lc). Herein,C_(st)=0.7 pF, C_(gd)=0.07 pF, and C_(lc)=0.75 pF over the entiredisplay region. FIG. 33A shows a state of distribution of C_(st), andFIG. 33B shows a state of distribution of C_(gd) (“normalized horizontalposition” on the horizontal axis refers to a value obtained bynormalizing a distance from the left end of a display region by adisplay region width, and the left end and the right end correspond to“0” and “1”). FIGS. 33C and 33D show the results for a DC average leveland a liquid crystal application voltage effective value. A DC averagelevel is larger in the portion away from the feeding ends (normalizedhorizontal position=1), compared with the portions close to the feedingends (normalizing horizontal position=0). A liquid crystal applicationvoltage effective value is smaller in the portion way from the feedingends (normalized horizontal position=1), compared with the portionsclose to the feeding ends (normalized horizontal position=0). Theseresults are as shown by (Formula 20) and (Formula 21). Furthermore, theshapes in FIGS. 33C and 33D are similar to that in FIG. 24.

Next, the case where a DC average level and a liquid crystal applicationvoltage effective value are uniform in a plane by giving an optimumdistribution in a display region to C_(st) and C_(gd) (making C_(lc)constant) will be shown as “capacitance gradient” in each figure.Herein, C_(st) and C_(gd) are selected so as to be matched with thevalues in the case of “no capacitance gradient) on the left end(normalized horizontal position=0). It is understood that if the valueof C_(st) is allowed to have a gradient of 0.7 pF (left end) to 0.745 pF(right end) as in FIG. 33A, and the value of C_(gd) is allowed to have agradient of 0.070 pF (left end) to 0.082 pF (right end) as in FIG. 33B,a DC average level and a liquid crystal application voltage effectivevalue become almost flat as in FIG. 33C or 33D (a distribution width iswithin 10 mV in any case).

If (Formula 25), (Formula 27), and the like are used at this time,β(O)=0<β(E)=0.0048, γ(O)=−2.303 V>γ(E)=−2.363 V are obtained, whichshows that the conditions of (Formula 29) and (Formula 31) aresatisfied. Furthermore, capacitance values in the middle (normalizedhorizontal position=0.5) between the portion close to the feeding endsand the portion away therefrom are read to be C_(st)=0.732 pF andC_(gd)=0.0785 pF, respectively, from FIGS. 33A and 33B. If β(M) and γ(M)described in (Principle 2 of the present invention: Optimum distributionof β and γ) are determined from the above capacitance values,β(M)=0.0034 and γ(M)=−2.345 V are obtained, which shows that thecondition of (Formula 34) also is satisfied.

(Embodiment 2)

In Embodiment 2 of the present invention, the configuration that reduceshorizontal crosstalk and lowers a voltage of a video signal drivingcircuit IC will be described with reference to FIGS. 4 and 5.

FIG. 4 is a plan view showing a pixel layout of a display apparatus ofthe second embodiment according to the present invention. Theconfiguration in FIG. 4 basically follows the pixel layout in FIG. 1. InFIG. 4, pixels are inverted in the vertical direction per column. Inthis layout, in order not to disturb the symmetry in the verticaldirection, a common electrode 4 is disposed in the middle between twoscanning electrodes 1. An insulating film 18 (not shown) is interposedbetween the pixel electrode and the common electrode to form a storagecapacitor 7 (C_(st)).

FIG. 5 is a circuit configuration diagram of a display apparatus of thesecond Embodiment according to the present invention. Basically, thisalso is the same as that in FIG. 3. However, pixels are inverted in thevertical direction per column, corresponding to the layout in FIG. 4.What is important here is that storage capacitance connected to (aplurality of) pixel electrodes of pixels belonging to one scanningelectrode (e.g., G₁), (ON/OFF of which is controlled by the scanningelectrode G₁), are connected to two common electrodes (C₀ and C₁) thatare the other connection destinations. Furthermore, the circuitconfiguration of the second embodiment also is characterized in thatpixels belonging to one scanning electrode (e.g., G₁) are present indifferent stages between the even-number column and the odd-numberedcolumn (note: this is not necessarily a required configuration of thepresent invention).

When such a configuration is used, dot inversion driving and columninversion driving also can be adopted, as well as line inversion driving(in the first embodiment, only line inversion or field inversion isadopted). This will be described with reference to FIGS. 5, 6A, and 6B,exemplifying dot inversion.

FIGS. 6A and 6B are waveform diagrams of an odd-number frame and aneven-number frame for illustrating a method for driving a displayapparatus of the second embodiment according to the present invention bydot inversion driving. The case will be considered in which signals withdifferent polarities are applied to video signal electrodes S₁ (and S₃,S₅, . . . , S_(n), . . . ) and S₂ (and S₄, S₆, . . . , S_(n+1), . . . )in an odd-number frame as shown in FIG. 6A. Now, for example, in ahorizontal scanning period (1H period) in which the scanning electrodeG₁ is selected, a positive signal V_(sig)(+) and a negative signalV_(sig)(−) are applied to S₁ and S₂ in FIG. 5, respectively. At thistime, in a column belonging to S₁ (more exactly, a column belonging to avideo signal electrode including S₁ to which a positive video signal isapplied), an upper pixel of G₁ (referred to as a “pixel P”) is in an ONstate, and in a column belonging to S₂ (more exactly, a column belongingto a video signal electrode including S₂ to which a negative videosignal is applied), a lower pixel of G₁ (referred to as “pixel Q”) is inan ON state.

Herein, the common electrodes that are connection destinations ofstorage capacitance of the pixels P and Q are C₀ and C_(l), respectively(these electrodes will be referred to as the first common electrode andthe second common electrode, based on G₁). These electrodes are separateones, so that they can be set at different potentials, i.e, C₀ (firstcommon electrode) is set to be V_(c)(+) (corresponding to the statewhere the pixel P is charged positively), and C₁ (second commonelectrode) is set to be V_(c)(−) (corresponding to the state where thepixel P is charged negatively). When the pixel P or Q is seen alone, therelationship of potentials among a video signal electrode, a scanningelectrode, and a common electrode is the same as that in FIG. 15, whichshows that the effect of an increase in an amplitude of a pixelelectrode potential as described in the Background Art with reference toFIGS. 14 and 15 can be obtained. Herein, the case has been described inwhich G₁ is selected. However, if the case where G₀ or G₂ is selected isconsidered similarly, it is understood that the potential waveform ofeach common electrode should be set as shown in FIG. 6A. This alsoapplies to the even-numbered frame shown in FIG. 6B, in which only thepolarities of signals of a video signal electrode and a common electrodeare reversed.

The above description also applies to the case of column inversion. Whenconsidered in the same way as in FIGS. 6A and 6B, it is understood thatby setting the potential waveform of a common electrode as shown inFIGS. 7A and 7B, the effect of an increase in an amplitude of a pixelelectrode potential as described in the Background Art with reference toFIGS. 14 and 15 can be obtained.

As described above, in the present embodiment, dot inversion or columninversion driving, which is a driving method advantageous with respectto horizontal crosstalk, is adopted, and the effect of an increase in anamplitude of a pixel electrode retention potential can be obtained.Thus, the reduction in horizontal crosstalk and the decrease in avoltage of a video signal driving circuit IC can be achieved. Morespecifically, the second object among the previously described twoobjects can be achieved.

It should be noted that the above-mentioned effect (reduction inhorizontal crosstalk and decrease in a voltage of a video signal drivingcircuit IC) can be obtained irrespective of the provision of adistribution of α_(st) and α_(gd) in a screen as described in(Description 1 of the principle of the present invention: Principle of areduction in a brightness gradient/flickering).

(Embodiment 3)

According to the above-mentioned second embodiment, the effect of anincrease in an amplitude of a pixel electrode retention potential asdescribed in JP 5(1993)-143021 can be obtained with dot inversiondriving or column inversion driving in the configurations of FIGS. 4 and5. If this is allowed to proceed further, it is apparent that what isdescribed in (Description 1 of the principle of the present invention:Principle of a reduction in a brightness gradient/flickering),(Principle 2 of the present invention: Optimum distribution of β and γ),(Supplementary item 1 regarding the principle: V_(cp) and ΔV_(cc)),(Supplementary item 2 regarding the principle: method for supplying apower of scanning electrodes and common electrodes), and (Supplementaryitem 3 regarding the principle: Another circuit configuration) isadopted as it is, and predetermined effects such as a reduction inflickering, a decrease in a brightness gradient, and the like can beobtained.

Actually, the layout in FIG. 4 shows the case where C_(st)(O)<C_(st)(E)and C_(gd)(O)<C_(gd)(E).

As a postscript, it is desirable that the video signal driving circuitbe designed for dot inversion or column inversion. More specifically, itis desirable that two kinds of video signals with different polaritiescan be applied simultaneously to a plurality of video signal electrodes,and for each video signal electrode, two kinds of video signals withdifferent polarities can be applied in accordance with a display period(depending upon whether a frame is an odd-number frame or an even-numberframe).

Furthermore, regarding common electrodes, based on a certain scanningelectrode, the number of common electrodes that are the other connectiondestinations of storage capacitance connected to pixel electrodesbelonging to the scanning electrode is two (first and second commonelectrodes in the above description). The number of common electrodes tobe connected is not necessarily two, and it may be three or more.However, if there are provided two common electrodes in accordance withthe polarity of a video signal, driving can be conducted mosteffectively at timings in FIGS. 6A and 6B, or FIGS. 7A and 7B, which isdesirable.

In FIG. 4, pixels in an even-number column and pixels in an odd-numbercolumn are completely symmetrical. However, considering the influence ofa shift of mask alignment and asymmetry regarding a scanning direction,capacitance values (C_(gd), C_(st), and the like) of these pixels may bemade different between the even-number column and the odd-number column.

In the case where signals with two polarities are applied simultaneouslyto a plurality of scanning electrodes, signals with opposite polaritiesare applied alternately on the column basis (more specifically,alternately between an even-number column and an odd-number column) indot inversion and column inversion. However, this is not necessarilyrequired. For example, each polarity may be arranged at every othercolumns or at random.

In FIGS. 4 and 5, pixels corresponding to two polarities are inverted inthe vertical direction. However, the present invention is not limitedthereto. More specifically, there may be a method for changing only theconnection destinations (common electrodes) of storage capacitance inaccordance with the polarity of a video signal electrode in theconfiguration shown in FIG. 1 or 3. In this case, in addition to theproblem of asymmetry of the configuration, wiring for connecting storagecapacitance crosses other scanning electrodes in a layout, whichgenerates an excess capacitance, leading to crosstalk. Thus, this is notdesirable.

(Embodiment 4)

In the fourth embodiment of the present invention, a display apparatususing liquid crystal in an In Plane Switching (IPS) mode will bedescribed with reference to FIGS. 9 and 10.

FIG. 9 is a plan view showing a pixel layout of a display apparatus ofthe fourth embodiment according to the present invention. FIG. 10 is across-sectional view taken along a line A-A′ in FIG. 1.

In FIGS. 9 and 10, reference numerals 11 and 12 denote substrates madeof glass or the like. Reference numeral 11 denotes an array substrate onwhich thin film transistors and electrodes connected thereto are formed,and reference numeral 12 denotes a counter substrate opposing the arraysubstrate. Liquid crystal 13 is interposed between two substrates, andboth ends thereof are sealed with a seal 17. Reference numerals 14 and15 denote polarizing plates for conducting a polarization display, and19 denotes a color filter for conducting a color display. Although thecolor filter is formed on the counter substrate 12 side, it may beformed on the array substrate 11 side.

On the array substrate 11, scanning electrodes 1 and common electrodes 4are formed of a first conductive layer, and an insulating film 18 coversthese electrodes. A pixel electrode 5 is formed of a second conductivelayer on the insulating film 18. As shown in FIG. 10, the pixelelectrode 5 overlaps the scanning electrode 1 of the previous stage. Theoverlapping portion with the scanning electrode 1 constitutes a storagecapacitor 7 (C_(st)). Furthermore, the overlapping portion of the pixelelectrode 5 and the scanning electrode 1 of the stage concernedconstitutes a scanning electrode-pixel electrode capacitance C_(gd).

As shown in FIG. 9, the common electrode 4 is provided with a branchedportion 4A. The branched portion 4A opposes the pixel electrode 5 inparallel, and works as a counter electrode for applying an electricfield to a liquid crystal layer. The capacitance between the pixelelectrode 5 and the common electrode 4 constitutes a commonelectrode-pixel electrode capacitance C_(lc). The capacitance betweenthe pixel electrode 5 and the common electrode 4 includes both acapacitance via the liquid crystal layer and a capacitance formed byboth electrodes that overlap each other geometrically. Although it isdifficult to calculate the capacitance via the liquid crystal layer byusing a mathematical formula or the like, it may be obtained by actualmeasurement or simulation.

The thin film transistor 3 is composed of a semiconductor portion 9 andthree electrodes. Gate electrodes are connected to the scanningelectrodes 1, source electrodes are connected to video signal electrodes2, and drain electrodes are connected to pixel electrodes 5.

FIG. 11 shows a circuit configuration of a display apparatus of thepresent embodiment using liquid crystal in an IPS mode. In FIG. 11, aunit pixel configuration shown in FIG. 8 are arranged in an array. Thescanning electrodes 1 are supplied with power from a scanning signaldriving circuit 21, and the video signal electrodes 2 are supplied withpower from a video signal driving circuit 22.

Now, the case will be considered where, in the circuit configuration ofFIG. 11, driving is conducted with a waveform as shown in FIG. 15 in thesame way as in the case of the circuit configuration (FIG. 13) in thefirst embodiment. When FIG. 3 (one pixel is shown in FIG. 14) iscompared with FIG. 11 (one pixel is shown in FIG. 8), the capacitancebetween the common electrode (V_(c)(n)) and the pixel electrode (V_(d))is C_(st) in the former case, whereas the capacitance between the commonelectrode (V_(c)(n)) and the pixel electrode (V_(d)) is C_(lc) in thelatter case. Therefore, a formula corresponding to the conservation ofcharge (Formula 11) in the case of FIG. 3 is given by the following(Formula 39):C_(gd)(V_(sig)(−)−V_(gon))+  (Formula 39)C_(lc)(V_(sig)(−)−V_(c)(−))+C_(st)(V_(sig)(−)−V_(goff))=C_(gd)(V_(do)(−)−V_(goff))+C_(lc)(V_(do)(−)−V_(coff))+C_(st)(V_(do)(−)−V_(goff))C_(gd)(V_(sig)(+)−V_(gon))+C_(lc)(V_(sig)(+)−V_(c)(+))+C_(st)(V_(sig)(+)−V_(goff))=C_(gd)(V_(do)(+)−V_(goff))+C_(lc)(V_(do)(+)−V_(coff))+C_(st)(V_(do)(+)−V_(goff))Herein, the following is taken into consideration: when a scanningelectrode (V_(g)(n)) is selected, a scanning electrode (V_(g)(n−1)) ofthe previous stage has been selected, and the potential has becomeV_(goff). When (Formula 39) is modified, (Formula 40) is obtained.V_(do)(−)=V_(sig)(−)−α_(lc)ΔV_(c)(−)−α_(gd)ΔV_(gon)  (Formula 40)V_(do)(+)=V_(sig)(+)−α_(lc)ΔV_(c)(+)−α_(gd)ΔV_(gon)where ΔV_(gon), ΔV_(c)(+), and ΔV_(c)(−) are the same as those in(Formula 13), and α_(gd) and α_(lc) are represented by (Formula 41):α_(gd)=C_(gd)/C_(tot)α_(lc)=C_(lc)/C_(tot)αC_(tot)=C_(gd)+C_(lc)+C_(st)  (Formula 41)

When the above-mentioned results are compared with the case ((Formula12) to (Formula 14)) of the circuit configuration in FIG. 3, the onlydifference lies in that suffixes “st” and “lc” are opposite. This showsthat what is described in the Background Art, (Analysis of the problemsof the prior art), (Description 1 of the principle of the presentinvention: Principle of a reduction in a brightnessgradient/flickering), (Principle 2 of the present invention: Optimumdistribution of β and γ), (Supplementary item 1 regarding the principle:V_(cp) p and ΔV_(cc)), (Supplementary item 2 regarding the principle:method for supplying a power of scanning electrodes and commonelectrodes), and (Supplementary item 3 regarding the principle: Anothercircuit configuration) is applicable as it is to the case (FIG. 11) ofthe present configuration, if C_(st) (storage capacitance)→C_(lc),C_(lc)→C_(st), and α_(st)→α_(lc). More specifically, it is apparent thatpredetermined effects such as a reduction in flickering and a brightnessgradient, and the like are obtained in the same way as in the circuit inFIG. 3.

It is understood that, in FIG. 11 (and FIG. 8), a scanning electrode ofthe previous stage corresponds to the counter electrode (V_(f)) in FIG.3 (and FIG. 14), if it is considered that C_(st) is replaced by C_(lc).The scanning electrode of the previous stage has a potential V_(goff) ina non-selection state, when the scanning electrode of the stageconcerned is selected. Therefore, it is possible to consider that thescanning electrode of the previous stage is the same as the counterelectrode in FIG. 3. In other words, any electrode having the samepotential both during a selection period of the scanning electrode ofthe stage concerned and during a retention period can be used as aconnection destination of C_(st). Such an electrode may be any electrodeexcluding a common electrode opposing a pixel electrode via a displaymedium (liquid crystal: capacitance C_(lc)) and a scanning electrode ofthe stage concerned. Among them, a scanning electrode (which may be ofthe subsequent stage) excluding the scanning electrode of the stageconcerned, or a common electrode other than those opposing via C_(lc) isparticularly desirable.

(Embodiment 5)

FIG. 12 is a plan view showing a pixel layout of a display apparatus ofthe fifth embodiment according to the present invention. In this pixellayout, regarding liquid crystal in an IPS mode as in the fourthembodiment, a layout is inverted in the vertical direction on the columnbasis, in the same way as in the second embodiment in which a reductionin horizontal crosstalk and a decrease in a voltage of a video signaldriving circuit IC are realized.

FIG. 13 is a circuit configuration diagram of the display apparatus ofthe fifth embodiment according to the present invention. Thiscorresponds to the case where TN liquid crystal is used (i.e., FIG. 5showing the circuit configuration of the second embodiment).

When these are compared, it also can be considered that only suffixes“st” and “lc” are replaced. Thus, as described in the second embodiment,the effect of realizing dot inversion driving or column inversiondriving, and a decrease in a voltage of a video signal can be obtained.

(Embodiment 6)

In the above-mentioned fifth embodiment, the effect of an increase inamplitude of a pixel electrode retention potential is obtained asdescribed in JP 5(1993)-143021 with dot inversion driving or columninversion driving in the IPS-type configuration. If this is allowed toproceed further, it is apparent that what is described in (Description 1of the principle of the present invention: Principle of a reduction in abrightness gradient/flickering), (Principle 2 of the present invention:Optimum distribution of β and γ), (Supplementary item 1 regarding theprinciple: V_(cp) and ΔV_(cc)), (Supplementary item 2 regarding theprinciple: method for supplying a power of scanning electrodes andcommon electrodes), and (Supplementary item 3 regarding the principle:Another circuit configuration) is adopted as it is, and predeterminedeffects such as a reduction in flickering, a decrease in a brightnessgradient, and the like can be obtained (herein, it may be consideredthat C_(st) (storage capacitance)→C_(lc), C_(lc)→C_(st), α_(st)→α_(lc)).Furthermore, if the similar replacement is conducted with respect to thepostscript in the third embodiment, the entire configuration of thesixth embodiment is established.

Hereinafter, other embodiments of the present invention will bedescribed.

(Exemplary Configuration in the Case where a Common Electrode Potentialis Not Controlled)

The case will be considered where a common electrode potential is notcontrolled, and a constant potential always is supplied. In this case, acommon electrode potential control circuit is not required. Thiscorresponds to the case where V_(c)(+)=V_(c)(−)=V_(coff) in the presentinvention. According to (Formula 19), ΔV_(cc)=0 and V_(cp)=0. In thiscase, γ(O)=γ(E)=0 from (Formula 25). Therefore, (Formula 29) is notsatisfied, and the effect of enhancement of a brightness gradient cannotbe obtained. However, since β(O)=α_(gd)(O), β(E)=α_(gd)(E) from (Formula27), it is possible to suppress flickering so as to satisfy (Formula 31)i.e., α_(gd)(O)<α_(gd)(E).

In particular, the case will be considered where scanning electrodes aresupplied with a power from one side, and the potential of commonelectrodes is fixed on both sides (more specifically, a constant voltageis supplied). In this case, a recharge voltage is generated as shown inFIG. 26C. In this manner, a recharge voltage is not increased withdistance from feeding ends of scanning electrodes, but there is atendency that a recharge voltage has a local maximum value at a certainposition, and decreases thereafter. Thus, it is desirable that thecorrection of α_(gd) should follow this. More specifically, for example,in the case where α_(gd) in a portion farthest from the feeding ends ofscanning electrodes is assumed to be α_(gd)(F), it is desirable thatthere is a position having a value of α_(gd) larger than α_(gd)(F)between the portion furthest from the feeding ends of the scanningelectrodes and the portion close thereto. This also applies to the casewhere scanning electrodes are supplied with a power from one side, andthe potential of the common electrodes is fixed only on the oppositeside, as in FIG. 26E.

(Exemplary Driving Method with Another Driving Waveform)

Exemplary voltage waveforms in the driving method of the presentinvention are shown in FIGS. 6A and 6B, FIGS. 7A and 7B, or FIG. 15. Inaddition to these, for example, it also is possible to use drivingwaveforms as in FIGS. 28A, 28B, 29A, and 29B.

FIGS. 28A and 28B show driving waveforms in the case of driving thecircuit with the configuration shown in FIG. 3 or 11. In FIG. 15, acommon electrode potential during a retention period is only one value,i.e., V_(coff); however, in the driving waveforms in FIGS. 28A and 28B,a common electrode potential during a retention period is notnecessarily one kind, and has two kinds of values, i.e., V_(c)(+) andV_(c)(−).

Now, the case of the circuit configuration in FIG. 3 is considered. Forexample, when a scanning electrode G₁ is selected, and pixel electrodesare charged with a negative signal (in the case of an odd-number framein FIG. 28A), the potential of a common electrode C_(lc) connected viastorage capacitance is V_(c)(−); however, the potential becomes V_(c)(+)during the subsequent retention period. Furthermore, when a scanningelectrode G₁ is selected, and a pixel electrode is charged with apositive signal (in the case of an even-number frame in FIG. 28B), thepotential of a common electrode C₁ is V_(c)(+); however, it becomesV_(c)(−) during the subsequent retention period. This also applies toother scanning electrodes, for example, G₀ and G₂.

In this case, when conservation of charge is considered in the same wayas described with respect to (Formula 11) in the Background Art,(Formula 42) is obtained.C_(gd)(V_(sig)(−)−V_(gon))+  (Formula 42)C_(st)(V_(sig)(−)−V_(c)(−))+C_(lc)(V_(sig)(−)−V_(f))=C_(gd)(V_(do)(−)−V_(goff))+C_(st)(V_(do)(−)−V_(c)(+))+C_(lc)(V_(do)(−)−V_(f))C_(gd)(V_(sig)(+)−V_(gon))+C_(st)(V_(sig)(+)−V_(c)(+))+C_(lc)(V_(sig)(+)−V_(f))=C_(gd)(V_(do)(+)−V_(goff))+C_(st)(V_(do)(+)−V_(c)(−))+C_(lc)(V_(do)(+)−V_(f))This is the formula obtained by changing V_(coff) of the second term(the term including C_(st)) of the right side to V_(c)(−) or V_(c)(+) inthe second formula of (Formula 11). If the following (Formula 43) isused in place of (Formula 13), (Formula 12) holds as it is.ΔV_(gon)=V_(gon)−V_(goff)ΔV_(c)(+)=V_(c)(+)−V_(c)(−)ΔV_(c)(−)=V_(c)(−)−V_(c)(+)  (Formula 43)More specifically, if ΔV_(c)(+) and ΔV_(c)(−) are read as in (Formula43), the following discussion (the principles and the like described in(Analysis of the problems of the prior art), (Description 1 of theprinciple of the present invention: Principle of a reduction in abrightness gradient/flickering), (Principle 2 of the present invention:Optimum distribution of β and γ), (Supplementary item 1 regarding theprinciple: V_(cp) and ΔV_(cc)), (Supplementary item 2 regarding theprinciple: method for supplying a power of scanning electrodes andcommon electrodes), (Supplementary item 3 regarding the principle:Another circuit configuration), and the like) are all applicable.

The formula type of (Formula 43) is different from that of (Formula 13).However, ΔV_(c)(+) or ΔV_(c)(−) also is a value of a potential (in thiscase, V_(c)(+) or V_(c)(−)) of a common electrode to which storagecapacitance is connected, at a moment when a pixel is charged, based ona potential (in this case, V_(coff)) in a retention state.

Even in the case using FIG. 11, the above description applies similarlyif C_(st) (storage capacitance)→C_(lc), C_(lc)→C_(st), α_(st)→α_(lc).

FIGS. 29A and 29B show driving waveforms in the case of driving acircuit with the configuration in FIG. 5 or 13. These driving waveformsare to be compared with those in FIGS. 6A and 6B. Also in this case, acommon electrode potential during a retention period is not necessarilyone kind, and has two kinds of values, i.e., V_(c)(+) and V_(c)(−).

Now, it is assumed that, in the circuit configuration in FIG. 5, forexample, a scanning electrode G₁ is selected, and pixel electrodesbelonging to a video signal electrode S₁ are charged with a positivesignal, and pixel electrodes belonging to a video signal electrode S₂are charged with a negative signal (the case of an odd-number frame inFIG. 29A). In this case, the potentials of common electrodes C₀ and C₁connected via storage capacitance are V_(c)(+) and V_(c)(−),respectively; however, they are V_(c)(−) and V_(c)(+), respectively,during a retention period. In contrast, when a scanning electrode G₁ isselected, and pixel electrodes belonging to a video signal electrode S₁are charged with a negative signal, and pixel electrodes belonging to avideo signal electrode S₂ are charged with a positive signal (the caseof an even-number frame in FIG. 29B), the potentials of commonelectrodes C₀ and C_(1 are Vc)(−) and V_(c)(+), respectively; however,they are V_(c)(+) and V_(c)(−), respectively, during a retention period.This also applies to other scanning electrodes, for example, G₀ and G₂.

More specifically, regarding any pixel electrode, when it is chargedwith a positive signal, the potential of a common electrode that is aconnection destination of storage capacitance always is V_(c)(+) andbecomes V_(c)(−) during a retention period. When a pixel electrode ischarged with a negative signal, the potential of a common electrode of aconnection destination of storage capacitance always is V_(c)(−) andbecomes V_(c)(+) during a retention period. Therefore, the sameconservation of storage as that of (Formula 42) holds, and by onlyreading ΔV_(c)(+) and ΔV_(c)(−) as in (Formula 43), what is described in(Analysis of the problems of the prior art), (Description 1 of theprinciple of the present invention: Principle of a reduction in abrightness gradient/flickering), (Principle 2 of the present invention:Optimum distribution of β and γ), (Supplementary item 1 regarding theprinciple: V_(cp) and ΔV_(cc)), (Supplementary item 2 regarding theprinciple: method for supplying a power of scanning electrodes andcommon electrodes), (Supplementary item 3 regarding the principle:Another circuit configuration), and the like is all applicable.

In the case of using the driving method in FIGS. 6A and 6B, FIGS. 7A and7B, or FIG. 15, three potential levels are required in a commonelectrode potential control circuit. However, in the case of the presentembodiment, only two potential levels are required. Thus, compared withthe driving method in FIGS. 6A and 6B, FIGS. 7A and 7B, or FIG. 15, theconfiguration of the common electrode potential control circuit can besimplified, and cost can be reduced.

(Case Where a Switching Element is Formed of a P-channel TFT)

Hitherto, an n-channel thin film transistor (which is turned on when agate potential is larger than a threshold voltage, and turned off when agate potential is smaller than a threshold voltage) has been assumed asa switching element. However, the above description also applies to thecase of a switching element of a p-channel TFT (which is turned off whena gate potential is larger than a threshold voltage, and turned on whena gate potential is smaller than a threshold voltage). What is describedin (Analysis of the problems of the prior art), (Description 1 of theprinciple of the present invention: Principle of a reduction in abrightness gradient/flickering), (Principle 2 of the present invention:Optimum distribution of β and γ), (Supplementary item 1 regarding theprinciple: V_(cp) and ΔV_(cc)), (Supplementary item 2 regarding theprinciple: method for supplying a power of scanning electrodes andcommon electrodes), (Supplementary item 3 regarding the principle:Another circuit configuration), and the like is all applicable. This isbecause the relationship formula of conservation of charge of (basic(Formula 11) (or (Formula 42)) holds irrespective of whether a switchingelement is of an n-channel type or a p-channel type.

However, it should be noted that, in the case of a p-channel thin filmtransistor, the relationship in magnitude between V_(gon) and V_(goff)generally is inverted, compared with the case of an n-channel thin filmtransistor. FIG. 30 shows a relationship in magnitude of a rechargevoltage corresponding to FIG. 18. Therefore, a relationship in magnitudeof a recharge voltage corresponding to (Formula 16) is represented by(Formula 44):|ΔV_(b)(O, +)|<|ΔV_(b)(E, +)||ΔV_(b)(O, −)|<|ΔV_(b)(E, −)||ΔV_(b)(O, +)|−|ΔV_(b)(O, −)|<|ΔV_(b)(E, +)|−|ΔV_(b)(E, −)|  (Formula 44)

In the case of a p-channel thin film transistor, a feedthrough voltagebecomes positive, and a recharge voltage becomes negative. Therefore, inthe above-mentioned formula, absolute value marks are provided. If theabsolute value marks are removed, (Formula 45) is obtained.ΔV_(b)(O, +)>ΔV_(b)(E, +)ΔV_(b)(O, −)>ΔV_(b)(E, −)ΔV_(b)(O, +)−ΔV_(b)(O, −)>ΔV_(b)(E, +)−ΔV_(b)(E, −)  (Formula 45)

When (Formula 45) is compared with (Formula 16), the third formulae arethe same, whereas the direction of inequality signs is opposite in thefirst and second formulae. Then, (Formula 21) holds as it is, whereasthe direction of an inequality sign becomes opposite in (Formula 20).

The conditions for eliminating a brightness gradient and flickering inthis case will be considered. First, as the condition for eliminating abrightness gradient, the same relationship as that of (Formula 29) isobtained from (Formula 28) and the third formula of (Formula 45).Furthermore, as the condition for eliminating flickering, the right sideof (Formula 30) becomes negative from the first and second formulae of(Formula 45). However, ΔV_(gon) also is negative, and the samerelationship as that of (Formula 31) can be obtained. More specifically,the condition for eliminating a brightness gradient and the conditionfor eliminating flickering are represented by the same formula,irrespective of whether a thin film transistor is an n-channel type or ap-channel type, and the configuration of the present invention is allapplicable.

(Case of the Configuration in which a Plurality of Lines are ScannedSimultaneously)

When liquid crystal is driven, one pixel may be charged twice or more inone frame (display period). For example, the following may be conducted:a video signal for conducting a black display is written after a videosignal is written in one frame, whereby blurring with respect toanimation is improved (generally, after 50 to 99% of a time in one framehas passed after a video signal is written, a video signal forconducting a black display often may be written). Alternatively,particularly in the case where OCB (optically compensated bend)-modeliquid crystal (which also may be called bend nematic LCD) is used, avideo signal for conducting a black display may be written for thepurpose of preventing reverse transition. Alternatively, a video signalmay be written for the purpose of conducting preliminary charging 1H to2H (1H is a horizontal period) before charging of a pixel is conducted.

In these cases, a video signal may be written to a plurality of linessimultaneously (more specifically, the potential of scanning electrodesin a plurality of lines is made V_(gon) simultaneously). For example,this corresponds to the case where a black signal is written to aplurality of lines simultaneously when a black display is conducted.Alternatively, preliminary charging may be conducted simultaneously withmain charging of the other pixels.

Even in the above-mentioned cases, if the potential of a commonelectrode to which each scanning electrode, which is to be V_(gon)simultaneously, is connected via storage capacitance (for example, inFIG. 3, C₁ with respect to G₁, and C₂ with respect to G₂) is varied inaccordance with the polarity of a video signal to be written, the effectof an increase in a signal amplitude can be obtained with respect toeach writing (charging). Thus, driving without inconsistency can beconducted.

(Supplemental Remarks with Respect to Cost of a Driving Circuit)

In the case of the present invention, since it is required to provide ascanning signal driving circuit and a common electrode potential controlcircuit (in the case of a general driving method in which the potentialof a common electrode is kept constant, a common electrode potentialcontrol circuit is not required), there may be apprehension that cost isincreased. However, if these driving circuits and pixel switchingelements are designed on the same layout in the stage of mask layoutdesign, extra processes do not result in the course of actualproduction, so that cost is not increased. In order to produce ascanning electrode driving circuit and a common electrode potentialcontrol circuit in the same substrate together with switching elements,it is desirable to use polycrystalline Si, single crystal Si, or SOI(silicon-on-insulator) type thin film transistor (or MOSFET). The reasonfor this is as follows. In the case of using these semiconductorsubstrates, either a p-channel thin film transistor or an n-channel thinfilm transistor can be produced, so that a degree of freedom for designof a driving circuit is enhanced.

(Case of a Current Driving Element)

An optical state of liquid crystal is controlled with an applied voltage(driving with a voltage), whereas an optical state of a self-emittingtype diode, laser, electroluminescence material generally is controlledwith a current (driving with a current). However, for example as shownin FIG. 31, if a pixel configuration is obtained in which a pixel TFTcontrols a gate potential of another auxiliary TFT 25 (also referred toas an auxiliary switching element), whereby a current flowing into anorganic electroluminescence element 24 is controlled, active matrix typedriving is made possible.

In this case, if the portion surrounded by a broken line is dealt withcollectively, this can be considered as if it is a display medium whoseoptical state is controlled with a voltage. Therefore, the configurationof the present invention is applicable. In this case, the sum of agate-source capacitance and a gate-drain capacitance of the auxiliaryTFT 25 may be considered to be C_(lc).

In such an element, it is not necessarily required to apply voltageswith positive and negative polarities (i.e., a.c. driving) to a gate ofthe auxiliary TFT 25. However, even in the case of d.c. driving when agate potential (potential of a portion represented by V_(g)(n) in FIG.31) falls, a distribution in a display region is caused in the potentialV_(d) due to the distribution of a recharge voltage in a display region.The reason for this is as follows. For example, when the first and thirdformulae (or second and fourth formulae) among four formulae of (Formula17) are compared with each other, a difference is caused betweenΔV_(b)(O, +) and ΔV_(b)(E, +), whereby the value of V_(do)(O, +) isdifferent from the value V_(do)(E, +). If a distribution is given toα_(st) or α_(gd) in a display region so as to shorten the distancebetween V_(do)(O, +) and V_(do)(E, +), a brightness gradient can beeliminated.

As described above, the effect of eliminating a brightness gradientcannot be obtained when γ=α_(st)V_(cp)/2 is a constant value in adisplay region. In other words, by setting the value of γ not to beconstant in a display region, the effect of eliminating a brightnessgradient can be obtained. As is understood from the descriptions of(Formula 12) to (Formula 14), γ refers to a difference in a capacitivecoupling voltage superimposed on pixel electrodes from common electrodesbetween the case where the polarity of a video signal is positive andthe case where the polarity of a video signal is negative (in otherwords, a difference between the application of a positive voltage to adisplay medium and the application of a negative voltage thereto). Morespecifically, the following also can be considered: a distribution of acapacitive coupling voltage is varied in a display region between theapplication of a positive voltage to a display medium and theapplication of a negative voltage thereto, whereby the effect ofeliminating a brightness gradient is obtained.

A capacitive coupling voltage superimposed on the pixel electrodes isnot necessarily from common electrodes. However, in order to adjust thepotential freely in synchronization with the scanning electrodes, it isdesirable to use common electrodes.

A method for changing a value in a screen in the present inventionbasically is realized by setting such a layout intentionally (morespecifically, by setting a design mask figure intentionally). However,even if a design mask figure is created as in the prior art (morespecifically, layouts of a pixel P and a pixel Q are designed to beuniform in a screen without giving a difference therebetween), forexample, by intentionally shifting mask alignment in the course ofproduction, the effects of the present invention also can be obtained.

In order to change a capacitance value, it is easiest to change anoverlapping area of two conductive layers (or semiconductor layers) in acapacitance formed by allowing two conductive layers (or semiconductorlayers) to sandwich an insulating layer. However, the following also maybe possible: a gap between two conductive layers on a layout is changedby utilizing a capacitance caused by two conductive layers (orsemiconductor layers) that are not overlapped with each other in a planebut are close to each other. Furthermore, it may be possible to vary acapacitance by changing the thickness of an insulating layer or changinga dielectric constant in some cases.

In the above, correction of an in-plane distribution of a rechargevoltage has been described. However, it also is appreciated thatflickering and a brightness gradient caused by an error in a productionprocess (size shift and non-uniformity caused by alignment, omission,leaving, and the like) can be corrected by the same method as that ofthe present invention.

In order to correct inconsistency of generation of a recharge voltage onthe line basis, caused by a difference in the distance of a wiringportion from a scanning signal driving circuit to a screen end portionin respective lines, and a recharge voltage difference between thecentral portion and the upper and lower portions, caused by a fixedpotential at an upper end or a lower end of the counter electrodeparticularly in the case of the configuration in FIG. 2, α_(st) andα_(gd) may be changed for each line.

In the above, the scanning signal driving circuit supplies a power fromthe upper side. However, it may supply a power from the lower side, orfrom upper and lower sides. Furthermore, the scanning signal drivingcircuit may supply a power alternately to every other column.

In the above, a scanning signal is supplied from the left (or right)side, and a video signal is supplied from the upper (or lower) side.However, the present invention is applicable to a display apparatus inwhich a scanning signal is supplied from the upper (or lower) side, anda video signal is supplied from the left (or right) side.

In the above-mentioned embodiments, a display apparatus has beendescribed, which refers to the entire apparatus including a scanningsignal driving circuit and a video signal driving circuit. In contrast,a portion at least including an array substrate, a counter substrate,and liquid crystal, without including a driving circuit, particularly isreferred to as a “display element”. The effects of the present inventioncan be obtained both in a display apparatus and a display element.

As the liquid crystal, a liquid crystal other than the above-mentionedTN liquid crystal and IPS liquid crystal may be used. VA (verticalalignment) liquid crystal having relatively high response speed and ahigh contrast may be used. Alternatively, MVA (multi-domain VA) liquidcrystal or other liquid crystal may be used. For example, TN (twistednematic) liquid crystal, STN (super twisted nematic) liquid crystal, ECB(electric field control birefringence) type liquid crystal including VAliquid crystal (vertical alignment liquid crystal or homeotropic liquidcrystal), homogeneous alignment liquid crystal, and the like, bentliquid crystal, IPS (in-plane switching) liquid crystal, GH (guest-host)liquid crystal, polymer dispersion type liquid crystal, ferroelectricliquid crystal, antiferroelectric liquid crystal, OCB liquid crystal,discotic liquid crystal, and other various modes can be used. Liquidcrystal may be of a normally white type (a transmittance is decreasedwith an increase in an applied voltage) or a normally black type (atransmittance is increased with an increase in an applied voltage.Furthermore, in addition to liquid crystal, a material whose opticalcharacteristics are changed with an applied voltage may be used. Forexample, electrooptical liquid crystal such as BSO (bismuth siliconoxide) and the like can be used. Furthermore, an electrochromicmaterial, a self-emitting diode, laser, electroluminescence material,and the like may be used. Alternatively, a DMD (deformable mirrordevice) and the like may be used. Since liquid crystal is leastexpensive, it is desirable to use liquid crystal.

In the above-mentioned embodiments, a direct-vision type liquid crystaldisplay panel has been described mainly. However, the present inventionalso is applicable to a liquid crystal element (including apolycrystalline Si type, a single crystal Si type, SOI(silicon-on-insulator) type, and the like) used in a liquid crystalprojector.

In the first to third embodiments, a display apparatus of a TN typeconfiguration (more generally, a configuration in which a pixelelectrode and a counter electrode form a parallel plate capacitance witha liquid crystal layer interposed therebetween) has been described. Inthe fourth to sixth embodiments, a display apparatus with an IPS typeconfiguration (more generally, a configuration in which a commonelectrode and a pixel electrode are formed on the same substrate, andliquid crystal is operated with an electric field parallel to thesubstrate) has been described.

However, the first to third embodiments, i.e., the unit pixel circuitconfiguration in FIG. 14 may be implemented with an IPS typeconfiguration. For example, a common electrode (potential V_(c)(n)) anda counter electrode (potential V_(f)) only need to be producedseparately on a substrate (the counter electrode may be separated on theline basis or column basis).

Furthermore, the fourth to sixth embodiments, i.e., the unit pixelcircuit configuration in FIG. 8 may be implemented with a TN-typeconfiguration. In this case, a counter electrode formed on a substrateon a counter side plays a role as a common electrode. Generally, acounter electrode is one electrode formed over the entire surface of adisplay region. Therefore, it is required that the potential takeseither V_(c)(+) or V_(c)(−) while the entire screen is scanned. However,the effects of the present invention are obtained similarly. In thiscase, V_(coff) may be considered to be an average value, i.e.,[V_(c)(+)+V_(c)(−)]/2 (in this case, according to (Formula 19),ΔV_(cc)=0, so that the effect of enhancement of stability with timedescribed in (Supplementary item 1 regarding the principle: V_(cp) andΔV_(cc)) cannot be expected).

Needless to say, if a counter electrode is insulated on the line basiswith a TN-type configuration, the potential of the counter electrode ineach line can be set separately, and the fourth to sixth embodiments canbe implemented as they are.

As a modified driving method of the present invention, there is a methodfor varying while keeping common electrodes or a counter electrode atthe same potential, for example, in the unit pixel circuit configurationin FIGS. 8 and 14 (synchro gate driving method). For example, in FIG.14, in the case where a video signal given by a video signal electrodeis positive, a counter electrode potential V_(f) and a common electrodepotential V_(c)(n) are set to be a first potential, and in the casewhere the video signal is negative, these potentials are set to be asecond potential. In this case, the connection destinations (morespecifically, V_(c)(n) and V_(f)) of C_(st) and C_(lc) in FIG. 14 havethe same potentials. Therefore, C_(st) and C_(lc) can be consideredmerely as a parallel capacitance, and C_(st)+C_(lc) can be considered tobe equivalent to C_(lc) in FIG. 8 (C_(st) in FIG. 8 may be 0).

Furthermore, the above-mentioned first potential may be considered to beV_(c)(+), the second potential may be considered to be V_(c)(−), andV_(coff) may be considered to be an average value thereof, i.e.,[V_(c)(+)+V_(c)(−)]/2 (in this case, according to (Formula 19),ΔV_(cc)=0, so that the effect of enhancement of stability with timedescribed in (Supplementary item 1 regarding the principle: V_(cp) andΔV_(cc)) cannot be expected).

1. A display apparatus, comprising: a plurality of pixel electrodesarranged in a matrix; switching elements connected thereto; scanningelectrodes; video signal electrodes; common electrodes; a counterelectrode; a display medium interposed between the pixel electrodes andthe counter electrode; and storage capacitance formed between the pixelelectrodes and the common electrodes, wherein, in a case where ascanning electrode-pixel electrode capacitance between the pixelelectrodes and the scanning electrodes is represented by C_(gd), acommon electrode-pixel electrode capacitance between the pixelelectrodes and the common electrodes is represented by C_(st), and atotal capacitance connected electrically to the pixel electrodes isrepresented by C_(tot), α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)  are set to bedifferent values between a portion close to feeding ends in a screen anda portion away therefrom, and an area of overlapping portions betweenthe scanning electrodes and the pixel electrodes, and an area ofoverlapping portions between the common electrodes and the pixelelectrodes are set to be larger in a screen center portion farthest fromthe feeding ends than in a screen end portion closest to the feedingends, so that α_(gd) and α_(st) are both larger in the screen centerportion farthest from the feeding ends than in the screen end portionclosest to the feeding ends.
 2. A display apparatus according to claim1, comprising a video signal driving circuit for applying two kinds ofvideo signals having different polarities to video signal electrodes inaccordance with a display period.
 3. A display apparatus according toclaim 2, comprising a common electrode potential control circuit forapplying a voltage signal to a plurality of common electrodes and ascanning signal driving circuit for applying a voltage signal to aplurality of scanning electrodes, the common electrode potential controlcircuit has output potential levels of at least two values, and thescanning signal driving circuit has output potential levels of at leasttwo values.
 4. A display apparatus according to claim 3, wherein thescanning signal driving circuit conducts writing to a plurality of linessimultaneously.
 5. A display apparatus according to claim 4, wherein thedisplay medium is liquid crystal of an OCB mode.
 6. A display apparatusaccording to claim 3, wherein the scanning signal driving circuit andthe common electrode potential control circuit are formed on the samesubstrate as that of the switching elements.
 7. A display apparatusaccording to claim 1, wherein the display medium is liquid crystal.
 8. Adisplay apparatus according to claim 7, which has a configurationforming a parallel plate capacitance in which a liquid crystal layer isinterposed between the pixel electrodes and the counter electrode.
 9. Adisplay apparatus according to claim 1, wherein at least one ofcapacitances forming C_(tot) includes a capacitance formed by twoconductive layers or semiconductor layers sandwiching an insulatinglayer therebetween, and an overlapping area of the two conductive layersor semiconductor layers is made different between the portion close tothe feeding ends in the screen and the portion away therefrom, wherebyα_(st) or α_(lc), and α_(gd) are allowed to have different valuesbetween the portion close to the feeding ends in the screen and theportion away therefrom.
 10. A method for driving the display apparatusof claim 1, wherein after a potential is written to the pixel electrodesvia the switching elements, a voltage is superimposed via C_(st) and hasa value different between the portion close to the feeding ends in thescreen and the portion away therefrom.
 11. A method for driving adisplay apparatus according to claim 10, wherein, when a scanningelectrode is selected, a first potential level V_(c)(+) is applied tocommon electrodes that are connection destinations of storagecapacitance connected to pixel electrodes of a plurality of pixelsbelonging to the scanning electrode in a case where a polarity of avideo signal is positive, and a second potential level V_(c)(−) isapplied thereto in a case where a polarity of the video signal isnegative.
 12. A display apparatus according to claim 1, wherein thedisplay medium is composed of a medium whose optical state is controlledwith a current and auxiliary switching elements.
 13. A display apparatusaccording to claim 12, wherein the medium whose optical state iscontrolled with a current is an organic electroluminescence medium. 14.A display apparatus, comprising: a plurality of pixel electrodesarranged in a matrix; switching elements connected thereto; scanningelectrodes; video signal electrodes; common electrodes; a counterelectrode; a display medium interposed between the pixel electrodes andthe counter electrode; storage capacitance formed between the pixelelectrodes and the common electrodes; a video signal driving circuit forapplying two kinds of video signals having different polarities to videosignal electrodes in accordance with a display period; and a commonelectrode potential control circuit for applying a voltage signal to aplurality of common electrodes and a scanning signal driving circuit forapplying a voltage signal to a plurality of scanning electrodes, thecommon electrode potential control circuit has output potential levelsof at least two values, and the scanning signal driving circuit hasoutput potential levels of at least two values, wherein, in a case wherea scanning electrode-pixel electrode capacitance between the pixelelectrodes and the scanning electrodes is represented by C_(gd), acommon electrode-pixel electrode capacitance between the pixelelectrodes and the common electrodes is represented by C_(st), and atotal capacitance connected electrically to the pixel electrodes isrepresented by C_(tot), α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)  are set to bedifferent values between a portion close to feeding ends in a screen anda portion away therefrom, a potential of a scanning electrode becomes afirst potential level V_(gon) when the scanning electrode is selectedand becomes substantially a second potential level V_(goff) during aretention period in which the scanning electrode is not selected, apotential of a common electrode that is a connection destination ofstorage capacitance connected to pixel electrodes of a plurality ofpixels belonging to the scanning electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal is positiveand a second potential level V_(c)(−) in a case where the polarity ofthe video signal is negative, when the scanning electrode is selected,and in a case where a difference between the first potential levelV_(c)(+) of the common electrode and a potential during a subsequentretention period is represented by ΔV_(c)(+), and a difference betweenthe second potential level V_(c)(−) of the common electrode and apotential during a subsequent retention period is represented byΔV_(c)(−), γ represented byγ=α_(st)V_(cp)/2  (Formula 2)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 3))  is set to be smaller inthe portion away from the feeding ends in the screen, compared with theportion close thereto.
 15. A display apparatus according to claim 14,wherein, assuming that a value of γ in the portion close to the feedingends in the screen is γ(O), a value of γ in the portion away from thefeeding ends in the screen is γ(E), and a value of γ in a portion in amiddle therebetween in terms of a distance is γ(M), γ(M) is smaller than[γ(O)+γ(E)]/2.
 16. A display apparatus according to claim 14, whereinV_(cp) takes a negative value.
 17. A display apparatus according toclaim 14, wherein a common electrode potential is different between aretention period after the pixel electrodes are charged with a positivevideo signal and a retention period after the pixel electrodes arecharged with a negative video signal.
 18. A display apparatus,comprising: a plurality of pixel electrodes arranged in a matrix;switching elements connected thereto; scanning electrodes; video signalelectrodes; common electrodes; a counter electrode; a display mediuminterposed between the pixel electrodes and the counter electrode;storage capacitance formed between the pixel electrodes and the commonelectrodes; a video signal driving circuit for applying two kinds ofvideo signals having different polarities to video signal electrodes inaccordance with a display period; and a common electrode potentialcontrol circuit for applying a voltage signal to a plurality of commonelectrodes and a scanning signal driving circuit for applying a voltagesignal to a plurality of scanning electrodes, the common electrodepotential control circuit has output potential levels of at least twovalues, and the scanning signal driving circuit has output potentiallevels of at least two values, wherein, in a case where a scanningelectrode-pixel electrode capacitance between the pixel electrodes andthe scanning electrodes is represented by C_(gd), a commonelectrode-pixel electrode capacitance between the pixel electrodes andthe common electrodes is represented by C_(st), and a total capacitanceconnected electrically to the pixel electrodes is represented byC_(tot), α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)  are set to bedifferent values between a portion close to feeding ends in a screen anda portion away therefrom, a potential of a scanning electrode becomes afirst potential level V_(gon) when the scanning electrode is selectedand becomes substantially a second potential level V_(goff) during aretention period in which the scanning electrode is not selected, apotential of a common electrode that is a connection destination ofstorage capacitance connected to pixel electrodes of a plurality ofpixels belonging to the scanning electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal is positiveand a second potential level V_(c)(−) in a case where the polarity ofthe video signal is negative, when the scamming electrode is selected,and in a case where a difference between the first potential levelV_(c)(+) of the common electrode and a potential during a subsequentretention period is represented by ΔV_(c)(+), and a difference betweenthe second potential level V_(c)(−) of the common electrode and apotential during a subsequent retention period is represented byΔV_(c)(−), β represented byβ=α_(gd)+α_(st)(ΔV_(cc)/ΔV_(gon))  (Formula 4)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 5))  is set to be larger inthe portion away from the feeding ends in the screen, compared with theportion close thereto.
 19. A display apparatus according to claim 18,wherein, assuming that a value of β in the portion close to the feedingends in the screen is β(O), a value of β in the portion away from thefeeding ends in the screen is β(E), and a value of β in a portion in amiddle therebetween in terms of a distance is β(M), β(M) is larger than[β(O)+β(E)]/2.
 20. A display apparatus according to claim 18, whereinΔV_(cc) is negative.
 21. A display apparatus, comprising: a plurality ofpixel electrodes arranged in a matrix; switching elements connectedthereto; scanning electrodes; video signal electrodes; commonelectrodes; a counter electrode; a display medium interposed between thepixel electrodes and the counter electrode; storage capacitance formedbetween the pixel electrodes and the common electrodes; a video signaldriving circuit for applying two kinds of video signals having differentpolarities to video signal electrodes in accordance with a displayperiod; and a common electrode potential control circuit for applying avoltage signal to a plurality of common electrodes and a scanning signaldriving circuit for applying a voltage signal to a plurality of scanningelectrodes, the common electrode potential control circuit has outputpotential levels of at least two values, and the scanning signal drivingcircuit has output potential levels of at least two values, wherein, ina case where a scanning electrode-pixel electrode capacitance betweenthe pixel electrodes and the scanning electrodes is represented byC_(gd), a common electrode-pixel electrode capacitance between the pixelelectrodes and the common electrodes is represented by C_(st), and atotal capacitance connected electrically to the pixel electrodes isrepresented by C_(tot), α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)  are set to bedifferent values between a portion close to feeding ends in a screen anda portion away therefrom, a potential of a scanning electrode becomes afirst potential level V_(gon) when the scanning electrode is selectedand becomes substantially a second potential level V_(goff) during aretention period in which the scanning electrode is not selected, apotential of a common electrode that is a connection destination ofstorage capacitance connected to pixel electrodes of a plurality ofpixels belonging to the scanning electrode becomes a first potentiallevel V_(c)(+) in a case where a polarity of a video signal is positiveand a second potential level V_(c)(−) in a case where the polarity ofthe video signal is negative, when the scanning electrode is selected,in a case where a difference between the first potential level V_(c)(+)of the common electrode and a potential during a subsequent retentionperiod is represented by ΔV_(c)(+), and a difference between the secondpotential level V_(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV_(c)(−), γ representedbyγ=α_(st)V_(cp)/2  (Formula 2)(where V_(cp)=ΔV_(c)(+)−ΔV_(c)(−)  (Formula 3))  is set to be smaller inthe portion away from the feeding ends in the screen, compared with theportion close thereto, and βrepresented byβ=α_(gd)+α_(st)(ΔV_(cc)/ΔV_(gon))  (Formula 4)(where ΔV_(gon)=V_(gon)−V_(goff),ΔV_(cc)=[ΔV_(c)(+)+ΔV_(c)(−)]/2  (Formula 5))  is set to be larger inthe portion away from the feeding ends in the screen, compared with theportion close thereto.
 22. A display element, comprising: a plurality ofpixel electrodes arranged in a matrix; switching elements connectedthereto; scanning electrodes; video signal electrodes; commonelectrodes; a counter electrode; a display medium interposed between thepixel electrodes and the counter electrode; and storage capacitanceformed between the pixel electrodes and the common electrodes, wherein,in a case where a scanning electrode-pixel electrode capacitance betweenthe pixel electrodes and the scanning electrodes is represented byC_(gd), a common electrode-pixel electrode capacitance between the pixelelectrodes and the common electrodes is represented by C_(st), and atotal capacitance connected electrically to the pixel electrodes isrepresented by C_(tot), α_(gd) and α_(st) represented byα_(gd)=C_(gd)/C_(tot), α_(st)=C_(st)/C_(tot)  (Formula 1)  are set to bedifferent values between a portion close to feeding ends in a screen anda portion away therefrom, and an area of overlapping portions betweenthe scanning electrodes and the pixel electrodes, and an area ofoverlapping portions between the common electrodes and the pixelelectrodes are set to be larger in a screen center portion farthest fromthe feeding ends than in a screen end portion closest to the feedingends, so that α_(gd) and α_(st) are both larger in the screen centerportion farthest from the feeding ends than in the screen end portionclosest to the feeding ends.
 23. A method of displaying an image on anapparatus comprising a plurality of pixel electrodes arranged in amatrix, a counter electrode, and a display medium interposed between thepixel electrodes and the counter electrode, the method, comprising:applying a signal to video signal electrodes connected to switchingelements connected to the pixel electrodes, the apparatus furthercomprising scanning electrodes and counter electrodes; and therebycausing activation of the display medium to display an image; wherein,when a scanning electrode-pixel electrode capacitance between the pixelelectrodes and the scanning electrodes is represented by C _(gd) , acommon electrode-pixel electrode capacitance between the pixelelectrodes and the common electrodes is represented by C _(st) , and atotal capacitance connected electrically to the pixel electrodes isrepresented by C _(tot), α_(gd) and α _(st) represented byα_(gd) =C _(gd) /C _(tot) , α _(st) =C _(st) /C _(tot)  (Formula 1 ) are set to be different values between a portion close to feeding endsin a screen and a portion away therefrom, and a flickering or brightnessgradient of the display can be reduced.
 24. The method according toclaim 23, wherein storage capacitance is formed between the pixelelectrodes and the common electrodes, an area of overlapping portionsbetween the scanning electrodes and the pixel electrodes, and an area ofoverlapping portions between the common electrodes and the pixelelectrodes are set to be larger in a screen center portion farthest fromthe feeding ends than in a screen end portion closest to the feedingends, so that α_(gd) and α _(st) are both larger in the screen centerportion farthest from the feeding ends than in the screen end portionclosest to the feeding ends.
 25. The method according to claim 23,wherein the display medium is liquid crystal, a storage capacitance isformed between each of electrodes, other than the common electrodesopposing the pixel electrodes via the display medium and the scanningelectrodes of the stage concerned, and the pixel electrodes, and thecommon electrodes are formed in a same substrate as are the pixelelectrodes, the liquid crystal being activated by an electric fieldparallel to the substrate.
 26. The method according to claim 25, whereina video signal driving circuit applies two kinds of video signals havingdifferent polarities to video signal electrodes in accordance with adisplay period.
 27. The method according to claim 26, wherein a commonelectrode potential control circuit applies a voltage signal to aplurality of common electrodes and a scanning signal driving circuitapplies a voltage signal to a plurality of scanning electrodes, whereinthe common electrode potential control circuit has output potentiallevels of at least two values, and the scanning signal driving circuithas output potential levels of at least two values.
 28. The methodaccording to claim 27, wherein a potential of a scanning electrodebecomes a first potential level V_(gon) when the scanning electrode isselected and becomes substantially a second potential level V _(goff)during a retention period in which the scanning electrode is notselected, a potential of a common electrode that opposes pixelelectrodes of a plurality of pixels belonging to the scanning electrodevia the display medium becomes a first potential level V _(c)(+) in acase where a polarity of a video signal is positive and a secondpotential level V _(c)(−) in a case where the polarity of the videosignal is negative, when the scanning electrode is selected, and in acase where a difference between the first potential level V _(c)(+) ofthe common electrode and a potential during a subsequent retentionperiod is represented by ΔV _(c)(+), and a difference between the secondpotential level V _(c)(−) of the common electrode and a potential duringa subsequent retention period is represented by ΔV _(c)(−), γrepresented byγ=α_(st) V _(cp) /2   (Formula 7 )(where V _(cp) =ΔV _(c)(+)−ΔV _(c)(−)  (Formula 8 ))  is set to besmaller in the portion away from the feeding ends in the screen,compared with the portion close thereto.
 29. The method according toclaim 28, wherein, assuming that a value of γ in the portion close tothe feeding ends in the screen is γ(O), a value of γ in the portion awayfrom the feeding ends in the screen is γ(E), and a value of γ in aportion in a middle therebetween in terms of a distance is γ(M), γ(M) issmaller than [γ(O)+γ(E)]/2.
 30. The method according to claim 28,wherein V_(cp) is negative.
 31. The method according to claim 27,wherein a potential of a scanning electrode becomes a first potentiallevel V_(gon) when the scanning electrode is selected and becomessubstantially a second potential level V _(goff) during a retentionperiod in which the scanning electrode is not selected, a potential of acommon electrode that opposes pixel electrodes of a plurality of pixelsbelonging to the scanning electrodes via the display medium becomes afirst potential level V _(c)(+) in a case where a polarity of a videosignal is positive and a second potential level V _(c)(−) in a casewhere the polarity of the video signal is negative, when the scanningelectrode is selected, and in a case where a difference between thefirst potential level V _(c)(+) of the common electrode and a potentialduring a subsequent retention period is represented by ΔV _(c)(+), and adifference between the second potential level V _(c)(−) of the commonelectrode and a potential during a subsequent retention period isrepresented by ΔV _(c)(−), β represented byβ=α_(gd) +α _(st)(ΔV _(cc) /ΔV _(gon))  (Formula 9 )(where ΔV _(gon) =V _(gon) −V _(goff) , ΔV _(cc) =[ΔV _(c)(+)+ΔV_(c)(−)]/2   (Formula 10 ))  is set to be larger in the portion awayfrom the feeding ends in the screen, compared with the portion closethereto.
 32. The method according to claim 31, wherein, assuming that avalue of β in the portion close to the feeding ends in the screen isβ(O), a value of β in the portion away from the feeding ends in thescreen is β(E), and a value of β in a portion in a middle therebetweenin terms of a distance is β(M), β(M) is larger than [β(O)+β(E)]/2. 33.The method according to claim 31, wherein ΔV_(cc) is negative.
 34. Themethod according to claim 27, wherein a potential of a scanningelectrode becomes a first potential level V_(gon) when the scanningelectrode is selected and becomes substantially a second potential levelV _(goff) during a retention period in which the scanning electrode isnot selected, a potential of a common electrode that opposes pixelelectrodes of a plurality of pixels belonging to the scanning electrodevia the display medium becomes a first potential level V _(c)(+) in acase where a polarity of a video signal is positive and a secondpotential level V _(c)(−) in a case where the polarity of the videosignal is negative, when the scanning electrode is selected, in a casewhere a difference between the first potential level V _(c)(+) of thecommon electrode and a potential during a subsequent retention period isrepresented by ΔV _(c)(+), and a difference between the second potentiallevel V _(c)(−) of the common electrode and a potential during asubsequent retention period is represented by ΔV _(c)(−), γ representedbyγ=α_(st) V _(cp) /2   (Formula 7 )(where V _(cp) =ΔV _(c)(+)−ΔV _(c)(−)  (Formula 8 ))  is set to besmaller in the portion away from the feeding ends in the screen,compared with the portion close thereto, and β represented byβ=α_(gd) +α _(st)(ΔV _(cc) /ΔV _(gon))  (Formula 9 )(where ΔV _(gon) =V _(gon) −V _(goff) , ΔV _(cc) =[ΔV _(c)(+)+ΔV_(c)(−)]/2   (Formula 10 ))  is set to be larger in the portion awayfrom the feeding ends in the screen, compared with the portion closethereto.
 35. The method according to claim 25, wherein at least one ofcapacitances forming C_(tot) includes a capacitance formed by twoconductive layers or semiconductor layers sandwiching an insulatinglayer therebetween, and an overlapping area of the two conductive layersor semiconductor layers is made different between the portion close tothe feeding ends in the screen and the portion away therefrom, whereby α_(st) and α _(gd) are allowed to have different values between theportion close to the feeding ends in the screen and the portion awaytherefrom.
 36. The method according to claim 25, wherein after apotential is written to the pixel electrodes via the switching elements,a voltage is superimposed via C_(st) and has a value different betweenthe portion close to the feeding ends in the screen and the portion awaytherefrom.
 37. The method according to claim 36, wherein, when ascanning electrode is selected, a first potential level V_(c)(+) isapplied to common electrodes opposing pixel electrodes of a plurality ofpixels belonging to the scanning electrode via a display medium in acase where a polarity of a video signal is positive, and a secondpotential level V _(c)(−) is applied thereto in a case where a polarityof the video signal is negative.